Failures if room contains a user with no e2e devices #338
Description
Describe the bug
With the e2e code now merged, element call fails if a user with no e2e devices is participating in the call. This can happen either by user using different versions of EC which don;'t have e2e enabled or because there are stuck users left over from before e2e.
The failure mode (or one of them) is that a user starts talking and then never stops (an exception gets thrown and then never caught).