Issue #3584235 by batigolix: Fix deprecated strtoupper(null) and wrong default...

Boris Doesborgrequested to merge
issue/flags-3584235:3584235-error-adding-flag-mapping into 8.x-1.x

Issue #3584235 by batigolix: Fix deprecated strtoupper(null) and wrong default value in CountryMappingForm

The source country field used getFlag() instead of getSource() for its default value, which was both a logic error and caused a PHP 8.1+ deprecation warning when creating a new mapping (null passed to strtoupper).

Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com

Closes #3584235

Merge request reports