## Bug description
I added an event (that exists) to an action, and now my action hangs forever.

I added an insight viewed event

w/ filters `insight == RETENTION` and `same_retention_and_cohortizing_event = false` – this appears to have broken my action where it does not load and I cannot edit it.

Cannot reproduce this same behavior locally.


## Expected behavior
- The action loads if the schema is correct.
-  If there's erroneous data it should load and let me edit it.

## How to reproduce

1. Create an action on Posthog cloud, in our main app
2. Add 'insight viewed' with filters `insight == RETENTION` and `same_retention_and_cohortizing_event = false`
3. The action will spin forever

## Environment

- [x] PostHog Cloud
- [ ] self-hosted PostHog, version/commit: _please provide_

## Additional context

[Sentry error](https://sentry.io/organizations/posthog/issues/2378948964/?project=1899813&referrer=slack)

Console errors 
<img width="1607" alt="Screen Shot 2021-05-03 at 5 45 39 PM" src="https://user-images.githubusercontent.com/5965891/116950024-b0d7a280-ac38-11eb-93c8-245390240532.png">
<img width="1167" alt="Screen Shot 2021-05-03 at 5 51 34 PM" src="https://user-images.githubusercontent.com/5965891/116950026-b208cf80-ac38-11eb-96e1-6a8f018f650a.png">



#### *Thank you* for your bug report – we love squashing them!

ee/clickhouse/views/actions.py
date_from = filter.date_from or timezone.now()
    data = {}
    if filter.interval == "month":
        data.update(
            {"date_to": (date_from + relativedelta(months=1) - timedelta(days=1)).strftime("%Y-%m-%d %H:%M:%S")}
        )
    elif filter.interval == "week":
        data.update({"date_to": (date_from + relativedelta(weeks=1)).strftime("%Y-%m-%d %H:%M:%S")})
    elif filter.interval == "hour":
        data.update({"date_to": date_from + timedelta(hours=1)})
    elif filter.interval == "minute":
        data.update({"date_to": date_from + timedelta(minutes=1)})
    return Filter(data={**filter._data, **data})
def _process_content_sql(team: Team, entity: Entity, filter: Filter):
    filter = _handle_date_interval(filter)
    parsed_date_from, parsed_date_to, _ = parse_timestamps(filter=filter, team_id=team.pk)
    entity_sql, entity_params = format_entity_filter(entity=entity)
    person_filter = ""
    person_filter_params: Dict[str, Any] = {}
    if filter.breakdown_type == "cohort" and filter.breakdown_value != "all":
        cohort = Cohort.objects.get(pk=filter.breakdown_value)
        person_filter, person_filter_params = format_filter_query(cohort)
        person_filter = "AND distinct_id IN ({})".format(person_filter)
    elif (
        filter.breakdown_type == "person"
        and isinstance(filter.breakdown, str)