fix: applicant split in edit mode, drop create-mode agency checks

src/Form/Service/ParticipantEmailFieldHandler.php

@@ -14,7 +14,8 @@ use App\Form\Service\Abstract\AbstractParticipantFieldHandler;
  * BusPro requires a Mail-Adresse for every participant once a room is present and rejects the
  * step-3 Anfrage with 650 otherwise, children included. It does accept an address identical to
  * the Anmelder's, so children inherit the applicant's rather than being asked for one they
- * typically do not have. The value stays editable and stays mandatory.
+ * typically do not have. The value stays editable and stays mandatory. This happens in the
+ * create flow only; in edit mode the handler just stores what was submitted.
  *
  * The copy only ever fills a blank, so an address somebody typed is never overwritten. A later
  * correction to the applicant's own address therefore does not propagate to children who already
@@ -65,6 +66,13 @@ class ParticipantEmailFieldHandler extends AbstractParticipantFieldHandler
      */
     public function applyApplicantEmail(BookingDto $bookingDto, ParticipantDto $participant): void
     {
+        // Create mode only. An existing booking already carries whatever BusPro accepted, a
+        // blank may be intended where personal data is optional, and participant[0] is not
+        // reliably the applicant there.
+        if (BookingDto::MODE_CREATE !== $bookingDto->getMode()) {
+            return;
+        }
+
         if (false === $participant->isChild()) {
             return;
         }