Missing UUID fails run completely

[NobbZ]

If the generator encounters a UUID in the canonical data it crashes
instantly.

The user is then presented a stack that includes the offending UUID in
the reason.

This is not very userfriendly. Instead it should be prefered to ignore
the offending UUID as if it was set to false in the tests.toml and
generate a list in the background that would be presented to the user
at the end of the run.

Preferably in a way that makes it easily copy pastable into the
tests.toml.