EXI silently failed to send message due to unverified devices in a room.

[ara4n]

Steps to reproduce

1. Send two messages in quick succession in a room where a user has added an unverified device to their account.
2. First message local echoes (i think) but then the local echo vanishes entirely from the timeline - empirically it never gets sent.
3. Second message gets the red warning icon, which in turn gives (as expected):

However, the first msg is lost forever.

Outcome

What did you expect?

We should never ever lose messages.

What happened instead?

Presumably there's a race when handling verification state which means that messages sent in quick succession may get lost in the face of unverified devices - or, worse, the first msg sent gets lost whatever.

Your phone model

No response

Operating system version

No response

Application version

747

Homeserver

No response

Will you send logs?

Yes

[ara4n]

See also #3006 for a similar failure mode (albeit unrelated to verification pinning)