* fix: return 400 instead of 500 for invalid email in iCal generation Co-Authored-By: benny@cal.com <sldisek783@gmail.com> * test: add unit tests for error handling in generateIcsString Co-Authored-By: benny@cal.com <sldisek783@gmail.com> --------- Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>