Draft: Resolve #3221934 "Trustedcallbackinterface"
Closes #3221934 by adding TrustedCallbackInterface to SubscribeForm.php. Define the $value variable used in line 96. Add notation to fix empty form validation error message.
Edited by Chris Dart
Closes #3221934 by adding TrustedCallbackInterface to SubscribeForm.php. Define the $value variable used in line 96. Add notation to fix empty form validation error message.