Already rapified files throw unknown errors

[jonpas]

Pre-processing already pre-processed (rapified) files results in the following vague error:

error: Failed to build PBO:
Failed to parse config:
Failed to read input file:
stream did not contain valid UTF-8

It does not even give a file name.

Ideally those files would be skipped, but at least it should be logged what file it was.

[jonpas]

Would add, but not sure what are all the paths where it can come to that and I don't want to break some other error outputs.