fix sync crash

sync/signals.py

@@ -8,7 +8,7 @@ from authentication.models import Device
 from django.contrib.auth import get_user_model
 
 from .ws_sender import websocket_sender
-from .registry import device_registry, related_users_registry
+from .registry import device_registry, related_users_registry, model_registry
 
 import logging
 import traceback
@@ -53,8 +53,10 @@ def synchronization_notifications(sender, instance, created=False, **kwargs):
     # some classes are excluded in settings_app.py: SYNC_APPS
     if not isinstance(instance, BaseModel) and not isinstance(instance, User):
         return
-    # if isinstance(instance, DataAccess):
-    #     return
+
+    model_name = instance.__class__.__name__
+    if model_registry.get_model(model_name) is None:
+        return
 
     try:
         process_foreign_key_changes(sender, instance, **kwargs)
@@ -100,7 +102,6 @@ def save_model_log_if_possible(instance, signal, created):
         else:
             operation = ModelOperation.DELETE
 
-        model_name = instance.__class__.__name__
         store_id = None
         if isinstance(instance, SideStoreModel):
             store_id = instance.store_id
@@ -111,6 +112,7 @@ def save_model_log_if_possible(instance, signal, created):
         # user_ids = [user.id for user in users]
         # # print(f'users to notify: {user_ids}')
         # instance._users_to_notify = user_ids # save this for the post_save signal
+        model_name = instance.__class__.__name__
         save_model_log(users, operation, model_name, instance.id, store_id)
 
     else: