Sentry Issue: [POSTHOG-EU-3K](https://sentry.io/organizations/posthog/issues/3662211615/?referrer=github_integration)

```
ValidationError: {'events': [{'math': [ErrorDetail(string='"avg" is not a valid choice.', code='invalid_choice')]}]}
  File "posthog/api/insight.py", line 604, in trend
    serializer.is_valid(raise_exception=True)
  File "rest_framework/serializers.py", line 228, in is_valid
    raise ValidationError(self.errors)
```
posthog/models/entity/entity.py
"""Checks if this entity is a superset version of other. The ids match and the properties of (this) is a subset of the properties of (other)"""
        self_properties = Counter([str(prop) for prop in self.property_groups.flat])
        other_properties = Counter([str(prop) for prop in other.property_groups.flat])
        return self.id == other.id and len(self_properties - other_properties) == 0
    def get_action(self) -> Action:
        if self.type != TREND_FILTER_TYPE_ACTIONS:
            raise ValueError(
                f"Action can only be fetched for entities of type {TREND_FILTER_TYPE_ACTIONS}, not {self.type}!"
            )
        if self._action and not settings.TEST:
            return self._action
        try:
            self._action = Action.objects.get(id=self.id)
            return self._action
        except:
            raise ValidationError(f"Action ID {self.id} does not exist!")
    __repr__ = sane_repr("id", "type", "order", "name", "custom_name", "math", "math_property", "properties")
class ExclusionEntity(Entity, FunnelFromToStepsMixin):