Timeline corruption on develop - "Live timeline 0 is no longer live"

[ara4n]

I've seen this ~3 times today, and Travis is getting bitten by it repeatedly.

Symptoms are stacktrace of:

Caught /sync error Error: live timeline 0 is no longer live - it has a neighbouring timeline
    at Room../matrix-js-sdk/lib/models/room.js.Room.addLiveEvents (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:28527:19)
    at SyncApi../matrix-js-sdk/lib/sync.js.SyncApi._processRoomEvents (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:35245:10)
    at _callee9$ (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:34809:54)
    at tryCatch (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:49866:40)
    at Generator.invoke [as _invoke] (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:50100:22)
    at Generator.prototype.(anonymous function) [as next] (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:49918:21)
From previous event:
    at https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:34858:46
From previous event:
    at SyncApi._callee10$ (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:34657:74)
    at tryCatch (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:49866:40)
    at Generator.invoke [as _invoke] (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:50100:22)
    at Generator.prototype.(anonymous function) [as next] (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:49918:21)
From previous event:
    at SyncApi._processSyncResponse (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:34946:22)
    at SyncApi._callee7$ (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:34294:60)
    at tryCatch (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:49866:40)
    at Generator.invoke [as _invoke] (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:50100:22)
    at Generator.prototype.(anonymous function) [as next] (https://riot.im/develop/bundles/c0b74508d5644578d135/bundle.js:49918:21)
consoleObj.(anonymous function) @ rageshake.js:61
16:44:19.277 rageshake.js:61 

And a message you try to send gets stuck in localecho state at the bottom of the timeline (in practice it successfully sends).

[ara4n]

@turt2live can you rageshake?

[ara4n]

https://github.com/matrix-org/riot-web-rageshakes/issues/1217

[turt2live]

Past related issues (not as common as whatever happened in the last 24h):

• Freeze of Riot: /sync error Error: live timeline 0 is no longer live #8084
• Unresponsive with /sync error #7507

[lampholder]

We're declaring this not a release blocker since we have seen very limit incidence of it. One to keep an eye on, though.

[turt2live]

Latest symptom from https://github.com/matrix-org/riot-web-rageshakes/issues/1238 is #riot-dev was only showing ~50% of the messages received over /sync, which lead to me thinking I was replying to someone that already had an answer :(

[ara4n]

@richvdh observes:

yeah :/. I suspect it's in code I wrote
and happens when there's a fork in the DAG or something