core: fix error when propertymappings return complex value

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

authentik/core/api/propertymappings.py

@@ -19,6 +19,7 @@ from authentik.core.api.used_by import UsedByMixin
 from authentik.core.api.utils import MetaNameSerializer, PassiveSerializer, TypeCreateSerializer
 from authentik.core.expression.evaluator import PropertyMappingEvaluator
 from authentik.core.models import PropertyMapping
+from authentik.events.utils import sanitize_item
 from authentik.lib.utils.reflection import all_subclasses
 from authentik.policies.api.exec import PolicyTestSerializer
 
@@ -140,7 +141,9 @@ class PropertyMappingViewSet(
                 self.request,
                 **test_params.validated_data.get("context", {}),
             )
-            response_data["result"] = dumps(result, indent=(4 if format_result else None))
+            response_data["result"] = dumps(
+                sanitize_item(result), indent=(4 if format_result else None)
+            )
         except Exception as exc:  # pylint: disable=broad-except
             response_data["result"] = str(exc)
             response_data["successful"] = False