Using an invalid ion Asset ID with self hosted & no Oauth causes a crash

[r-veenstra]

As a byproduct of the fix for #702, users can encounter a scenario where entering an ion Asset Id that doesn't exist on the server causes a crash in OV, when using with no Oauth self hosted setups.

We likely need some sort of server side check to determine if the asset ID is actually valid, and prevent whatever is causing the crash if the asset doesn't exist.

This does not impact regular Saas ion from what I can tell, and most if not all production users should be running Oauth, so this should only be experienced by users experimenting with local deployments of self hosted.