## Bug description

While exploring the onboarding/setup funnel, I found what seems to be a bug capturing events (perhaps it's an API request issue). When I send this request, the events don't get saved (checked directly on the database).

```
POST <host>/capture
```

```json
{
    "api_key": "API_KEY_HERE",
    "event": "Purchase item",
    "properties": {
        "distinct_id": "845555992929291"
    }
}
```


## Expected behavior
- Events should be correctly saved to the database. If on the onboarding flow, continue the user and complete the onboarding.
- If the request is malformed or an invalid API key is sent, I should not receive a 200 status code. _There seems to be an issue with the request and therefore the event is not saved_, however **if I add a random non-existent key as the API key (e.g. `invalid`), I still get a 200 and a 1 in the response.**  


## Reproduction environment
- Tested using the one-line Docker deploy.
```bash
doker run -t -i --rm --publish 8000:8000 -v postgres:/var/lib/postgresql posthog/posthog:preview
```
- Tested on the cloud version with the same result (please reach out privately if you want to know the account's email address).

posthog/test/test_middleware.py
with self.settings(TOOLBAR_COOKIE_NAME="phtoolbar", TOOLBAR_COOKIE_SECURE=True):
            self.client.force_login(self.user)
            response = self.client.get("/")
            toolbar_cookie = response.cookies[settings.TOOLBAR_COOKIE_NAME]
            self.assertEqual(toolbar_cookie.key, "phtoolbar")
            self.assertEqual(toolbar_cookie.value, "yes")
            self.assertEqual(toolbar_cookie["path"], "/")
            self.assertEqual(toolbar_cookie["samesite"], "None")
            self.assertEqual(toolbar_cookie["httponly"], True)
            self.assertEqual(toolbar_cookie["domain"], "")
            self.assertEqual(toolbar_cookie["comment"], "")
            self.assertEqual(toolbar_cookie["secure"], True)
            self.assertEqual(toolbar_cookie["max-age"], 31536000)
    def test_logout(self):
        with self.settings(TOOLBAR_COOKIE_NAME="phtoolbar"):
            self.client.force_login(self.user)
            response = self.client.get("/")
            self.assertEqual(response.cookies[settings.TOOLBAR_COOKIE_NAME].key, "phtoolbar")
            self.assertEqual(response.cookies[settings.TOOLBAR_COOKIE_NAME].value, "yes")
            self.assertEqual(response.cookies[settings.TOOLBAR_COOKIE_NAME]["max-age"], 31536000)
            response = self.client.get("/logout")
            self.assertEqual(response.cookies[settings.TOOLBAR_COOKIE_NAME].key, "phtoolbar")
            self.assertEqual(response.cookies[settings.TOOLBAR_COOKIE_NAME].value, "")
            self.assertEqual(response.cookies[settings.TOOLBAR_COOKIE_NAME]["max-age"], 0)