We had some string mismatch issues that specifically affected

Shellcheck's usage, due to some of the capabilities used in the tool.

Byte strings were expected but Unicode strings returned. This change

fixes those up, as part of a larger block of work to add more strict

string type checks throughout the codebase.
PMD also had a regression due to changes for better error parsing. Some

code was removed that would have bailed out earlier if no files were

returned. This left a check in place to make sure there was only 1 file

in the results, which would fail if the report was empty. This case is

once again handled.

Unit tests pass.
Verified the fix with a customer.