fix(ffi): don't panic when joining after having cancelled a media upload

[bnjbvr]

Fixes #3573.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.71%. Comparing base (30f3a3c) to head (a66772b).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4141      +/-   ##
==========================================
- Coverage   84.72%   84.71%   -0.02%     
==========================================
  Files         269      269              
  Lines       28779    28779              
==========================================
- Hits        24384    24380       -4     
- Misses       4395     4399       +4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[poljar]

I wonder if we can disallow unwraps in the ffi crate.

[stefanceriu]

Can confirm that this isn't panicking anymore and that it still works propoperly. Will follow up though with a change on the iOS side to get rid of that extra cancellation call