Correction soumission anonyme

Fix #239

src/agenda_culturel/models.py

@@ -10,7 +10,7 @@ from colorfield.fields import ColorField
 from django_ckeditor_5.fields import CKEditor5Field
 from urllib.parse import urlparse
 from django.core.cache import cache
-from django.contrib.auth.models import User
+from django.contrib.auth.models import User, AnonymousUser
 import emoji
 
 import hashlib
@@ -935,6 +935,9 @@ class Event(models.Model):
         self.no_modification_date_changed = True
 
     def set_processing_user(self, user):
+        if user.is_anonymous:
+            self.processing_user = None
+        else:
             self.processing_user = user
 
     def set_in_moderation_process(self):