## 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/middleware.py
def process_response(self, request, response):
        response = super(ToolbarCookieMiddleware, self).process_response(request, response)
        
        if request.path.startswith("/api/") or request.path.startswith("/e/") or request.path.startswith("/decide/"):
            return response
        toolbar_cookie_name = settings.TOOLBAR_COOKIE_NAME  
        toolbar_cookie_secure = settings.TOOLBAR_COOKIE_SECURE  
        if (
            toolbar_cookie_name not in response.cookies
            and request.user
            and request.user.is_authenticated
            and request.user.toolbar_mode == "toolbar"
        ):
            response.set_cookie(
                toolbar_cookie_name,  
                "yes",  
                365 * 24 * 60 * 60,  
                None,  
                "/",  
                None,  
                toolbar_cookie_secure,  
                True,  
                "Lax",  
            )
            response.cookies[toolbar_cookie_name]["samesite"] = "None"  
        return response