[DSLX] Fix interpreter_main to display internal error messages explicitly.
[DSLX] Fix interpreter_main to display internal error messages explicitly.

Before it would just say "failed" and it would be unclear why. Of course,
internal error messages shouldn't rise to be exposed to the user typically, but
important to give some helpful indicator when they do!

PiperOrigin-RevId: 360731256

google/xls,google/xls,google/xls,google/xls,google/xls,google/xls