Fix: Various small bugs found during typing updates (#14593)

* Fix: match Apple Mail tag colors case-insensitively

* Fix: reject OAuth callbacks with an unrecognized scope

* Fix: refuse to refresh OAuth tokens for non-OAuth accounts or missing refresh tokens

* Fix: parse datetime strings in the format_datetime filter and reject invalid ones

* Fix: reject a PAPERLESS_URL without a hostname

* Fix: report a database error in the system status instead of failing with a 500

* Fix: surface the database error when refreshing a document before moving its files

* Fix: report no unapplied migrations when the applied migrations cannot be read

* Fix: return the parsed value directly in format_datetime for typing

* Chore: annotate the paperless_dirs fixture in the refresh failure test

* Allow null for the latest_migration system status type

---------

Co-authored-by: shamoon <4887959+shamoon@users.noreply.github.com>

src/documents/views.py

@@ -5268,7 +5268,9 @@ class CustomFieldViewSet(PermissionsAwareDocumentCountMixin, ModelViewSet[Custom
                             "migration_status": inline_serializer(
                                 name="MigrationStatus",
                                 fields={
-                                    "latest_migration": serializers.CharField(),
+                                    "latest_migration": serializers.CharField(
+                                        allow_null=True,
+                                    ),
                                     "unapplied_migrations": serializers.ListSerializer(
                                         child=serializers.CharField(),
                                     ),
@@ -5343,6 +5345,8 @@ class SystemStatusView(PassUserMixin):
         db_conn = connections["default"]
         db_url = str(db_conn.settings_dict["NAME"])
         db_error = None
+        all_migrations: list[str] = []
+        applied_migrations: list[str] = []
 
         try:
             db_conn.ensure_connection()
@@ -5353,7 +5357,8 @@ class SystemStatusView(PassUserMixin):
                 f"{m.app}.{m.name}"
                 for m in MigrationRecorder.Migration.objects.all().order_by("id")
             ]
-        except Exception as e:  # pragma: no cover
+        except Exception as e:
+            all_migrations = []
             applied_migrations = []
             db_status = "ERROR"
             logger.exception(
@@ -5549,7 +5554,9 @@ class SystemStatusView(PassUserMixin):
                     "status": db_status,
                     "error": db_error,
                     "migration_status": {
-                        "latest_migration": applied_migrations[-1],
+                        "latest_migration": (
+                            applied_migrations[-1] if applied_migrations else None
+                        ),
                         "unapplied_migrations": [
                             m for m in all_migrations if m not in applied_migrations
                         ],