* Add full-text search for authorized statuses
- Search API will return statuses that match the query
- Only for logged in users
- Only if you are author of the status,
- Or you were mentioned in it
- Or you favourited or reblogged it
- Configuration over `ES_ENABLED`, `ES_HOST`, `ES_PORT`, `ES_PREFIX`
- Run `rails chewy:deploy` to create & populate index
Fix#5880Fix#4293Fix#1152
* Add commented out docker-compose configuration for ES container
* Optimize index import, filter search results
* Add basic normalization to the index
* Add better stemming and normalization to the index
* Skip webfinger request if search query includes both @ and a space
* Fix code style
* Visually separate search result sections
* Fix code style issues
* When must_be_following_dm is on, only notify if recipient dm'ed user
Currently, when must_be_following_dm is on, if a user sends a direct
message replying to any status from the recipient, the recipient gets a
notification. This should not be the case, as if the recipient posted
something publicly this can be used to spam their notifications.
* Refactor replied_to_status_is_direct_message?
Following suggestion in PR
* Fix regeneration marker not being removed after completion
* Return HTTP 206 from /api/v1/timelines/home if regeneration in progress
Prioritize RegenerationWorker by putting it into default queue
* Display loading indicator and poll home timeline while it regenerates
* Add graphic to regeneration message
* Make "not found" indicator consistent with home regeneration
* Fix actors accepting invalid URI schemes or different host between URI and URL
* Fix statuses accepting invalid URI scheme or different host to actor
* Adjust tests to new requirements
* Improve readability of mismatching_origin?/invalid_origin? methods
without them, such as is the case with GNU social
Fixes the ability to find GNU social accounts via URL in search and
when using remote follow function
Avoid error when the service returns a mostly valid oembed, but has no
url in it, causing a MethodError: undefined method `url'
for #<OEmbed::Response::Photo:0x000056505def9620>
* Change conditional to avoid nil into string error in sidekiq
When obtaining information about users with mastodon in a different
subdomain, sidekiq was giving out a 'no implicit conversion of nil into String'
* Use presence instead of blank? with ternary.
Following suggestion on PR
* Add list of lists component to web UI
* Add list adding
* Add list removing
* List editor modal
* Add API account search limited by following=true relation
* Rework list editor modal
* Remove mandatory pagination of GET /api/v1/lists/:id/accounts
* Adjust search input placeholder
* Fix rspec (#5890)
* i18n: (zh-CN) Add missing translations for #5811 (#5891)
* i18n: (zh-CN) yarn manage:translations -- zh-CN
* i18n: (zh-CN) Add missing translations for #5811
* Fix some issues
- Display loading/missing state for list timelines
- Order lists alphabetically in overview
- Fix async list editor reset
- Redirect to /lists after deleting unpinned list
- Redirect to / after pinning a list
* Remove dead list columns when a list is deleted or fetch returns 404
* Add semi-support for Video/Image objects in ActivityPub
Video and Image objects will create corresponding status records
with manually crafted text contents (title + URL)
* Extract html-url-finding logic into JsonLdHelper
* Fallback to id when url missing, extract supported object types
* Avoid sending explicit Undo->Announce when original deleted
* Do not forward a reply back to the server that sent it
* Deduplicate inboxes of rebloggers' followers for delete forwarding
* Adjust test
* Fix wrong class, bad SQL, wrong variable, outdated comment
* Allow hiding of reblogs from followed users
This adds a new entry to the account menu to allow users to hide
future reblogs from a user (and then if they've done that, to show
future reblogs instead).
This does not remove or add historical reblogs from/to the user's
timeline; it only affects new statuses.
The API for this operates by sending a "reblogs" key to the follow
endpoint. If this is sent when starting a new follow, it will be
respected from the beginning of the follow relationship (even if
the follow request must be approved by the followee). If this is
sent when a follow relationship already exists, it will simply
update the existing follow relationship. As with the notification
muting, this will now return an object ({reblogs: [true|false]}) or
false for each follow relationship when requesting relationship
information for an account. This should cause few issues due to an
object being truthy in many languages, but some modifications may
need to be made in pickier languages.
Database changes: adds a show_reblogs column (default true,
non-nullable) to the follows and follow_requests tables. Because
these are non-nullable, we use the existing MigrationHelpers to
perform this change without locking those tables, although the
tables are likely to be small anyway.
Tests included.
See also <https://github.com/glitch-soc/mastodon/pull/212>.
* Rubocop fixes
* Code review changes
* Test fixes
This patchset closes#648 and resolves#3271.
* Rubocop fix
* Revert reblogs defaulting in argument, fix tests
It turns out we needed this for the same reason we needed it in muting:
if nil gets passed in somehow (most usually by an API client not passing
any value), we need to detect and handle it.
We could specify a default in the parameter and then also catch nil, but
there's no great reason to duplicate the default value.
* Add test for temporary account resolving failures in ProcessMentionsService
* Fix processing of mentions to already-known remote accounts on temporary failures
* Serialize moved accounts into REST and ActivityPub APIs
* Parse federated moved accounts from ActivityPub
* Add note about moved accounts to public profiles
* Add moved account message to web UI
* Fix code style issues
* Add structure for lists
* Add list timeline streaming API
* Add list APIs, bind list-account relation to follow relation
* Add API for adding/removing accounts from lists
* Add pagination to lists API
* Add pagination to list accounts API
* Adjust scopes for new APIs
- Creating and modifying lists merely requires "write" scope
- Fetching information about lists merely requires "read" scope
* Add test for wrong user context on list timeline
* Clean up tests
* Add a hide_notifications column to mutes
* Add muting_notifications? and a notifications argument to mute!
* block notifications in notify_service from hard muted accounts
* Add specs for how mute! interacts with muting_notifications?
* specs testing that hide_notifications in mutes actually hides notifications
* Add support for muting notifications in MuteService
* API support for muting notifications (and specs)
* Less gross passing of notifications flag
* Break out a separate mute modal with a hide-notifications checkbox.
* Convert profile header mute to use mute modal
* Satisfy eslint.
* specs for MuteService notifications params
* add trailing newlines to files for Pork :)
* Put the label for the hide notifications checkbox in a label element.
* Add a /api/v1/mutes/details route that just returns the array of mutes.
* Define a serializer for /api/v1/mutes/details
* Add more specs for the /api/v1/mutes/details endpoint
* Expose whether a mute hides notifications in the api/v1/relationships endpoint
* Show whether muted users' notifications are muted in account lists
* Allow modifying the hide_notifications of a mute with the /api/v1/accounts/:id/mute endpoint
* make the hide/unhide notifications buttons work
* satisfy eslint
* In probably dead code, replace a dispatch of muteAccount that was skipping the modal with launching the mute modal.
* fix a missing import
* add an explanatory comment to AccountInteractions
* Refactor handling of default params for muting to make code cleaner
* minor code style fixes oops
* Fixed a typo that was breaking the account mute API endpoint
* Apply white-space: nowrap to account relationships icons
* Fix code style issues
* Remove superfluous blank line
* Rename /api/v1/mutes/details -> /api/v2/mutes
* Don't serialize "account" in MuteSerializer
Doing so is somewhat unnecessary since it's always the current user's account.
* Fix wrong variable name in api/v2/mutes
* Use Toggle in place of checkbox in the mute modal.
* Make the Toggle in the mute modal look better
* Code style changes in specs and removed an extra space
* Code review suggestions from akihikodaki
Also fixed a syntax error in tests for AccountInteractions.
* Make AddHideNotificationsToMute Concurrent
It's not clear how much this will benefit instances in practice, as the
number of mutes tends to be pretty small, but this should prevent any
blocking migrations nonetheless.
* Fix up migration things
* Remove /api/v2/mutes
* Add option to block direct messages from people you don't follow
Fix#5326
* If the DM responds to a toot by recipient, allow it through
* i18n: Update Polish translation (for #5669) (#5673)
* Work around Twidere and Tootdon bug
Tootdon and Twidere construct @user@domain handles from mentions in toots based
solely on the mention text and account URI's domain without performing any
webfinger call or retrieving account info from the Mastodon server.
As a result, when a remote user has WEB_DOMAIN ≠ LOCAL_DOMAIN, Twidere and
Tootdon will construct the mention as @user@WEB_DOMAIN. Now, this will usually
resolve to the correct account (since the recommended configuration is to have
WEB_DOMAIN perform webfinger redirections to LOCAL_DOMAIN) when processing
mentions, but won't do so when displaying them (as it does not go through the
whole account resolution at that time).
This change rewrites mentions to the resolved account, so that displaying the
mentions will work.
* Use lookbehind instead of non-capturing group in MENTION_RE
Indeed, substitutions with the previous regexp would erroneously eat any
preceding whitespace, which would lead to concatenated mentions in the
previous commit.
Note that users will “lose” up to one character space per mention for their
toots, as that regexp is also used to remove the domain-part of mentioned
users for character counting purposes, and it also erroneously removed the
preceding character if it was a space.
* Resolve remote accounts when mentioned even if they are already known
This commit reduces the risk of not having up-to-date public key or protocol
information for a remote account, which is required to deliver toots
(especially direct messages).
* Do not add mentions in private messages for remote users we cannot deliver to
Mastodon does not deliver private and direct toots to OStatus users, as there
is no guarantee the remote software understands the toot's privacy. However,
users currently do not get any feedback on it (Mastodon won't attempt delivery,
but the toot will be displayed exactly the same way to the user).
This change introduces *some* feedback by not processing mentions that are
not going to be delivered. A long-term solution is still needed to have
delivery receipts or at least some better indication of what is going on, but
at least an user can see *something* is up.
This commit reduces the risk of not having up-to-date public key or protocol
information for a remote account, which is required to deliver toots
(especially direct messages).
Specifically, this fixes status length calculation to be same as JS side.
BTW, since this pattern used in not only preview card fetching, we
should extract it (with twitter-regex?) and write tests I think.
Remote ActivityPub users that have never been known as OStatus users
(whether or not they support it) will not have a “remote_url” attribute
set. In case they reside on an instance with WEB_DOMAIN ≠ LOCAL_DOMAIN,
the current check did rely on “remote_url” to verify the user's domain.
* If OEmbed response doesn't have a required property `type`, ignore it.
e.g. `NoMethodError: undefined method 'type' for ...`
* If we failed to detect encoding, fallback to default behavior of Nokogiri.
e.g. `KeyError: key not found: :encoding`
- Rename Mastodon::TimestampIds into Mastodon::Snowflake for clarity
- Skip for statuses coming from inbox, aka delivered in real-time
- Skip for statuses that claim to be from the future
* Improve error handling on LinkCrawlWorker
* Ignore TimeoutError and InvalidURIError too
* Record errors to debug log
* Enable dead job queue on LinkCrawlWorker
Since most of acceptable errors were already ignored, only our side issue should go to dead job queue.
* Ignore all http gem errors
The whole point of verified_webfinger? is to check the WebFinger-discoverable
URI maps back to the known author URI. This was not actually verified if the
first Webfinger request was not a redirection.
* Use non-serial IDs
This change makes a number of nontrivial tweaks to the data model in
Mastodon:
* All IDs are now 8 byte integers (rather than mixed 4- and 8-byte)
* IDs are now assigned as:
* Top 6 bytes: millisecond-resolution time from epoch
* Bottom 2 bytes: serial (within the millisecond) sequence number
* See /lib/tasks/db.rake's `define_timestamp_id` for details, but
note that the purpose of these changes is to make it difficult to
determine the number of objects in a table from the ID of any
object.
* The Redis sorted set used for the feed will have values used to look
up toots, rather than scores. This is almost always the same as the
existing behavior, except in the case of boosted toots. This change
was made because Redis stores scores as double-precision floats,
which cannot store the new ID format exactly. Note that this doesn't
cause problems with sorting/pagination, because ZREVRANGEBYSCORE
sorts lexicographically when scores are tied. (This will still cause
sorting issues when the ID gains a new significant digit, but that's
extraordinarily uncommon.)
Note a couple of tradeoffs have been made in this commit:
* lib/tasks/db.rake is used to enforce many/most column constraints,
because this commit seems likely to take a while to bring upstream.
Enforcing a post-migrate hook is an easier way to maintain the code
in the interim.
* Boosted toots will appear in the timeline as many times as they have
been boosted. This is a tradeoff due to the way the feed is saved in
Redis at the moment, but will be handled by a future commit.
This would effectively close Mastodon's #1059, as it is a
snowflake-like system of generating IDs. However, given how involved
the changes were simply within Mastodon, it may have unexpected
interactions with some clients, if they store IDs as doubles
(or as 4-byte integers). This was a problem that Twitter ran into with
their "snowflake" transition, particularly in JavaScript clients that
treated IDs as JS integers, rather than strings. It therefore would be
useful to test these changes at least in the web interface and popular
clients before pushing them to all users.
* Fix JavaScript interface with long IDs
Somewhat predictably, the JS interface handled IDs as numbers, which in
JS are IEEE double-precision floats. This loses some precision when
working with numbers as large as those generated by the new ID scheme,
so we instead handle them here as strings. This is relatively simple,
and doesn't appear to have caused any problems, but should definitely
be tested more thoroughly than the built-in tests. Several days of use
appear to support this working properly.
BREAKING CHANGE:
The major(!) change here is that IDs are now returned as strings by the
REST endpoints, rather than as integers. In practice, relatively few
changes were required to make the existing JS UI work with this change,
but it will likely hit API clients pretty hard: it's an entirely
different type to consume. (The one API client I tested, Tusky, handles
this with no problems, however.)
Twitter ran into this issue when introducing Snowflake IDs, and decided
to instead introduce an `id_str` field in JSON responses. I have opted
to *not* do that, and instead force all IDs to 64-bit integers
represented by strings in one go. (I believe Twitter exacerbated their
problem by rolling out the changes three times: once for statuses, once
for DMs, and once for user IDs, as well as by leaving an integer ID
value in JSON. As they said, "If you’re using the `id` field with JSON
in a Javascript-related language, there is a very high likelihood that
the integers will be silently munged by Javascript interpreters. In most
cases, this will result in behavior such as being unable to load or
delete a specific direct message, because the ID you're sending to the
API is different than the actual identifier associated with the
message." [1]) However, given that this is a significant change for API
users, alternatives or a transition time may be appropriate.
1: https://blog.twitter.com/developer/en_us/a/2011/direct-messages-going-snowflake-on-sep-30-2011.html
* Restructure feed pushes/unpushes
This was necessary because the previous behavior used Redis zset scores
to identify statuses, but those are IEEE double-precision floats, so we
can't actually use them to identify all 64-bit IDs. However, it leaves
the code in a much better state for refactoring reblog handling /
coalescing.
Feed-management code has been consolidated in FeedManager, including:
* BatchedRemoveStatusService no longer directly manipulates feed zsets
* RemoveStatusService no longer directly manipulates feed zsets
* PrecomputeFeedService has moved its logic to FeedManager#populate_feed
(PrecomputeFeedService largely made lots of calls to FeedManager, but
didn't follow the normal adding-to-feed process.)
This has the effect of unifying all of the feed push/unpush logic in
FeedManager, making it much more tractable to update it in the future.
Due to some additional checks that must be made during, for example,
batch status removals, some Redis pipelining has been removed. It does
not appear that this should cause significantly increased load, but if
necessary, some optimizations are possible in batch cases. These were
omitted in the pursuit of simplicity, but a batch_push and batch_unpush
would be possible in the future.
Tests were added to verify that pushes happen under expected conditions,
and to verify reblog behavior (both on pushing and unpushing). In the
case of unpushing, this includes testing behavior that currently leads
to confusion such as Mastodon's #2817, but this codifies that the
behavior is currently expected.
* Rubocop fixes
I could swear I made these changes already, but I must have lost them
somewhere along the line.
* Address review comments
This addresses the first two comments from review of this feature:
https://github.com/tootsuite/mastodon/pull/4801#discussion_r139336735https://github.com/tootsuite/mastodon/pull/4801#discussion_r139336931
This adds an optional argument to FeedManager#key, the subtype of feed
key to generate. It also tests to ensure that FeedManager's settings are
such that reblogs won't be tracked forever.
* Hardcode IdToBigints migration columns
This addresses a comment during review:
https://github.com/tootsuite/mastodon/pull/4801#discussion_r139337452
This means we'll need to make sure that all _id columns going forward
are bigints, but that should happen automatically in most cases.
* Additional fixes for stringified IDs in JSON
These should be the last two. These were identified using eslint to try
to identify any plain casts to JavaScript numbers. (Some such casts are
legitimate, but these were not.)
Adding the following to .eslintrc.yml will identify casts to numbers:
~~~
no-restricted-syntax:
- warn
- selector: UnaryExpression[operator='+'] > :not(Literal)
message: Avoid the use of unary +
- selector: CallExpression[callee.name='Number']
message: Casting with Number() may coerce string IDs to numbers
~~~
The remaining three casts appear legitimate: two casts to array indices,
one in a server to turn an environment variable into a number.
* Only implement timestamp IDs for Status IDs
Per discussion in #4801, this is only being merged in for Status IDs at
this point. We do this in a migration, as there is no longer use for
a post-migration hook. We keep the initialization of the timestamp_id
function as a Rake task, as it is also needed after db:schema:load (as
db/schema.rb doesn't store Postgres functions).
* Change internal streaming payloads to stringified IDs as well
This is equivalent to 591a9af356 from
#5019, with an extra change for the addition to FeedManager#unpush.
* Ensure we have a status_id_seq sequence
Apparently this is not a given when specifying a custom ID function,
so now we ensure it gets created. This uses the generic version of this
function to more easily support adding additional tables with timestamp
IDs in the future, although it would be possible to cut this down to a
less generic version if necessary. It is only run during db:schema:load
or the relevant migration, so the overhead is extraordinarily minimal.
* Transition reblogs to new Redis format
This provides a one-way migration to transition old Redis reblog entries
into the new format, with a separate tracking entry for reblogs.
It is not invertible because doing so could (if timestamp IDs are used)
require a database query for each status in each users' feed, which is
likely to be a significant toll on major instances.
* Address review comments from @akihikodaki
No functional changes.
* Additional review changes
* Heredoc cleanup
* Run db:schema:load hooks for test in development
This matches the behavior in Rails'
ActiveRecord::Tasks::DatabaseTasks.each_current_configuration, which
would otherwise break `rake db:setup` in development.
It also moves some functionality out to a library, which will be a good
place to put additional related functionality in the near future.
Additionally, ActivityPub::FetchRemoteStatusService no longer parses
activities.
OStatus::Activity::Creation no longer delegates to ActivityPub because
the provided ActivityPub representations are not signed while OStatus
representations are.
If the signature could not be verified and the webfinger of the account
was last retrieved longer than the cache period, try re-resolving the
account and then attempting to verify the signature again
- Previously they wouldn't receive it unless they were author's
followers
- Skip unpush from public/hashtag timelines if status wasn't
public in the first place
* Fix JavaScript interface with long IDs
Somewhat predictably, the JS interface handled IDs as numbers, which in
JS are IEEE double-precision floats. This loses some precision when
working with numbers as large as those generated by the new ID scheme,
so we instead handle them here as strings. This is relatively simple,
and doesn't appear to have caused any problems, but should definitely
be tested more thoroughly than the built-in tests. Several days of use
appear to support this working properly.
BREAKING CHANGE:
The major(!) change here is that IDs are now returned as strings by the
REST endpoints, rather than as integers. In practice, relatively few
changes were required to make the existing JS UI work with this change,
but it will likely hit API clients pretty hard: it's an entirely
different type to consume. (The one API client I tested, Tusky, handles
this with no problems, however.)
Twitter ran into this issue when introducing Snowflake IDs, and decided
to instead introduce an `id_str` field in JSON responses. I have opted
to *not* do that, and instead force all IDs to 64-bit integers
represented by strings in one go. (I believe Twitter exacerbated their
problem by rolling out the changes three times: once for statuses, once
for DMs, and once for user IDs, as well as by leaving an integer ID
value in JSON. As they said, "If you’re using the `id` field with JSON
in a Javascript-related language, there is a very high likelihood that
the integers will be silently munged by Javascript interpreters. In most
cases, this will result in behavior such as being unable to load or
delete a specific direct message, because the ID you're sending to the
API is different than the actual identifier associated with the
message." [1]) However, given that this is a significant change for API
users, alternatives or a transition time may be appropriate.
1: https://blog.twitter.com/developer/en_us/a/2011/direct-messages-going-snowflake-on-sep-30-2011.html
* Additional fixes for stringified IDs in JSON
These should be the last two. These were identified using eslint to try
to identify any plain casts to JavaScript numbers. (Some such casts are
legitimate, but these were not.)
Adding the following to .eslintrc.yml will identify casts to numbers:
~~~
no-restricted-syntax:
- warn
- selector: UnaryExpression[operator='+'] > :not(Literal)
message: Avoid the use of unary +
- selector: CallExpression[callee.name='Number']
message: Casting with Number() may coerce string IDs to numbers
~~~
The remaining three casts appear legitimate: two casts to array indices,
one in a server to turn an environment variable into a number.
* Back out RelationshipsController Change
This was made to make a test a bit less flakey, but has nothing to
do with this branch.
* Change internal streaming payloads to stringified IDs as well
Per
https://github.com/tootsuite/mastodon/pull/5019#issuecomment-330736452
we need these changes to send deleted status IDs as strings, not
integers.
* Support OpenGraph video embeds
It's not really OpenGraph, it's twitter:player property, but it's
not OEmbed so that fits. For example, this allows Twitch clips to
be displayed as embeds.
Also, fixesglitch-soc/mastodon#135
* Fix invalid OpenGraph cards being saved through attaching and
revisit URLs after 14 days
* Whenever a remote keypair changes, unfollow them and re-subscribe to them
In Mastodon (it could be different for other OStatus or AP-enabled software),
a keypair change is indicative of whole user (or instance) data loss. In this
situation, the “new” user might be different, and almost certainly has an empty
followers list. In this case, Mastodon instances will disagree on follower
lists, leading to unreliable delivery and “shadow followers”, that is users
believed by a remote instance to be followers, without the affected user
knowing.
Drawbacks of this change are:
1. If an user legitimately changes public key for some reason without losing
data (not possible in Mastodon at the moment), they will have their remote
followers unsubscribed/re-subscribed needlessly.
2. Depending of the number of remote followers, this may generate quite some
traffic.
3. If the user change is an attempt at usurpation, the remote followers will
unknowingly follow the usurper. Note that this is *not* a change of
behavior, Mastodon already behaves like that, although delivery might be
unreliable, and the usurper would not have known the former user's
followers.
* Rename ResubscribeWorker to RefollowWorker
* Process followers in batches
When a new user confirms their e-mail, bootstrap their home timeline
by automatically following a set of accounts. By default, all local
admin accounts (that are unlocked). Can be customized by new admin
setting (comma-separated usernames, local and unlocked only)
- Fix assumption that `url` is always a string. Handle it if it's an
array of strings, array of objects, object, or string, both for
accounts and for objects
- `sharedInbox` is actually supposed to be under `endpoints`, handle
both cases and adjust the serializer
* Make "unfollow" undo pending outgoing follow request too
* Add cancel button to web UI when awaiting follow request approval
* Make the hourglass button do the cancelling
Using _: property names is discouraged, as in the future,
canonicalization may throw an error when encountering that instead
of discarding it silently like it does now.
We are defining some ActivityStreams properties which we expect
to land in ActivityStreams eventually, to ensure that future versions
of Mastodon will remain compatible with this even once that happens.
Those would be `locked`, `sensitive` and `Hashtag`
We are defining a custom context inline for some properties which we
do not expect to land in any other context. `atomUri`, `inReplyToAtomUri`
and `conversation` are part of the custom defined OStatus context.
* Make PreviewCard records reuseable between statuses
**Warning!** Migration truncates preview_cards tablec
* Allow a wider thumbnail for link preview, display it in horizontal layout (#4648)
* Delete preview cards files before truncating
* Rename old table instead of truncating it
* Add mastodon:maintenance:remove_deprecated_preview_cards
* Ignore deprecated_preview_cards in schema definition
* Fix null behaviour
* Guarantee Subscription service first account has proper URL details
Subscription Service potentially could break if the first user suspended
themselves, creating a situation where the urls that populate throughout
subscription service's PuSH request would cause the remote API to throw 503 errors.
Guaranteeing that the first account picked is not suspended prevents this problem.
* Fix style issue
Requires moving Atom rendering from DistributionWorker (where
`stream_entry.status` is already nil) to inline (where
`stream_entry.status.destroyed?` is true) and distributing that.
Unfortunately, such XML renderings can no longer be easily chained
together into one payload of n items.
* Add handling of Linked Data Signatures in payloads
* Add a way to sign JSON, fix canonicalization of signature options
* Fix signatureValue encoding, send out signed JSON when distributing
* Add missing security context
* Process Create / Announce activity in FetchRemoteStatusService
* Use activity URL in ActivityPub for reblogs
* Redirect to the original status on StatusesController#show
* Ignore empty response in ActivityPub::FetchRemoteStatusService
This fixes `NoMethodError: undefined method `[]' for nil:NilClass` error.
* Check json.nil? in JsonLdHelper#supported_context?
