[DB] Potential Bug: sending NULL via umami.trackView(String, NULL)

[foxytocin]

It is possible to accidentally write NULL to the database. Did so accidentally for [referrer] value.

umami.trackView(url, [referrer])

Usage:
umami.trackView('/home', NULL);

When displaying the details page with the referrer statistics in the browser, this leads to the following error
Browser: 'An unexpected error has occurred.'
Console:

Fantastic project, best regards

[mikecao]

That's def a bug, we should guard against that.

[foxytocin]

Made a PR to fix the issue by checking also against ref !== null so that the illegal access of property startsWith doesn't happend. Works fine for the detailed view of the dashboard but doesn't guard against entering null to the DB.

Error case: