BUGFIX: Prevent the node editor from breaking for nodes with hashes

[rolandschuetz]

Fixes #59

[Benjamin-K]

This will show links like node://XXXXXX#section as they are without resolving the node, right?
At least the editor can be used for such links, but IMO the main goal should be to see the selected node, too.
Nevertheless, this is way better than the current behavior. But the same check should then be used for assets, too.

[rolandschuetz]

Exactly, since there was no decision on how the UI should look, this is just a bugfix preventing an internal server error and broken UI.

[Benjamin-K]

Could you add asset:// links with hashes to this PR, too? That would be awesome!

[rolandschuetz]

@Benjamin-K Makes sense, I added it together with some tests