UI doesn't render if custom.js missing

[takluyver]

We load custom/custom.js using require along with all of our own modules, and page.show() is called in the success callback for that require call. So if there's a 404 on custom.js, you're left with a blank page, and only a message at the JS console says what the problem is.

We should load custom.js separately, since it doesn't matter if it's not there.

It would also be good to have something more informative than a blank page if something fails to load, but that's not the focus of this issue.

[minrk]

It shouldn't be possible for custom.js to be missing. This is a bug introduced by #16.

[minrk]

Actually, this doesn't appear to be true. I ran master without any custom.js, and it loads fine.

[takluyver]

Well, I ran master and it didn't load, but when I commented out the 'custom/custom' line in main.js, it worked. Maybe it was cached when you tried?

[minrk]

I can't seem to make it 404. Did you restart your nbserver? #16 changed the URL for custom from /static/custom to /custom since it's handled specially. What do you see at http://localhost:8888/custom/custom.js?

[takluyver]

Ah, I must have pulled while I had a notebook server running. Sorry about that.