when firing up an old matrix client, all your interactive verification requests arrive again

[ara4n]

i just had all the interactive verif reqs reappear on syncing a client for the first time in a few months. what's more, i couldn't reliably cancel them (either due to the X button not working, or the app being so overloaded it didn't respond to clicks

[turt2live]

I suspect this is the same cause as #8629

[turt2live]

I think the X not working is https://github.com/matrix-org/matrix-js-sdk/pull/961/files#diff-0a3445e771f0c35ffee76e9d08b65e12R175

[turt2live]

Trivial reproduction steps:

1. Close Bob's client
2. Have Alice start a verification
3. Have Alice cancel that verification
4. Start Bob's client

Bob then receives an unexpected verification request, and a silenced error about an unhandled m.key.verification.cancel event.