rails/journey — comment on commit 70d101b3386ba26ff801cec496da9c23389434aa
File:  line 0
By cgunther:

@artellectual are you sure you're not mistakenly passing `nil` or something that evaluates to `nil` to a URL helper somewhere?

Watch out for passing unsaved model objects to URL helpers, even though they are not `nil` themselves, calling `#to_param` on them returns `nil` which was the cause of my problems.