fix(base): Remove a panic in a log

[Hywan]

We must not panic if the event has no event ID.

[stefanceriu]

👍

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.60%. Comparing base (fff270d) to head (a8241c6).
⚠️ Report is 4 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...k-base/src/response_processors/room/msc4186/mod.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5851   +/-   ##
=======================================
  Coverage   88.59%   88.60%           
=======================================
  Files         361      361           
  Lines      102287   102287           
  Branches   102287   102287           
=======================================
+ Hits        90624    90632    +8     
+ Misses       7444     7435    -9     
- Partials     4219     4220    +1     

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[codspeed-hq]

CodSpeed Performance Report

Merging #5851 will not alter performance

_{Comparing Hywan:fix-base-panic-in-log (a8241c6) with main (fff270d)}

Summary

✅ 50 untouched