Exception on trying to edit non-existent prefix

[plajjan]

If you go to /prefix/edit/123123123, ie a prefix ID that doesn't exist, an exception is thrown. We should probably catch this somewhere in the web frontend and display a somewhat friendlier error message.

[dosomder]

Same for pools and vrfs

[plajjan]

I think we'll wait with this until we have Angularified those pages. I really don't want to put much more effort into them right now.

[plajjan]

Putting this on Hades. Let's see if it's reproducible on AngularJS version of the page.

[plajjan]

With the introduction of AngularJS, the error has changed, now we instead get some other JS traceback because it expects to receive certain data that it doesn't receive.