policies: fix error when error occurs during policy process with no target

authentik/policies/engine.py

@@ -82,8 +82,10 @@ class PolicyEngine:
 
     def _iter_bindings(self) -> Iterator[PolicyBinding]:
         """Make sure all Policies are their respective classes"""
-        return PolicyBinding.objects.filter(target=self.__pbm, enabled=True).order_by(
-            "order"
+        return (
+            PolicyBinding.objects.filter(target=self.__pbm, enabled=True)
+            .order_by("order")
+            .iterator()
         )
 
     def _check_policy_type(self, policy: Policy):

authentik/policies/models.py

@@ -64,7 +64,10 @@ class PolicyBinding(SerializerModel):
         return PolicyBindingSerializer
 
     def __str__(self) -> str:
-        return f"Policy Binding {self.target} #{self.order} {self.policy}"
+        try:
+            return f"Policy Binding {self.target} #{self.order} {self.policy}"
+        except PolicyBinding.target.RelatedObjectDoesNotExist:  # pylint: disable=no-member
+            return f"Policy Binding - #{self.order} {self.policy}"
 
     class Meta: