Can't reject or accept an invite

[MarcWadai]

There can be situations where the invite is stuck and the user cannot remove it. And the notifications seems also to be stuck.

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Tests

Test 1

• Invite a user B with user A
• See the notification on user B without doing anything else
• delete the room with user A
• Accept the invite with user B -> an error popup is displaying (normal because the room doesnt exist yet)
• Reject the invite -> the notification and invite disappear well

Test 2

• Invite a user B with user A
• See the notification on user B without doing anything else
• Remove the invite
• The invite and notification disappear for user B

Test 3

Same as test 2 but with two users on different instance (over federation) !

• We get a stuck notification and cannot refuse the invite
• When we accept the notification this popup show up
  
• When we reject the invite, this popup is displayed
  

Test 4

There should be another situation where the user click accept on the invite but get an error 502 :

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Steps to reproduce :

• See test 3

TODO

There is an open ticket on synapse side regarding this issue element-hq/synapse#4808