If so, could you create a 'shut-up' command for debugging, which if read in the script, could set a flag so that error-handling could be by-passed in favour of a quick program dropout with just a simple "Error" msg despite whatever the cause (and perhaps including the last parsed line number if that is possible). At least that could show if it was the error-handing that was causing the problems.
It might also be worth considering if a 'single-step' feature was possible, because it could certainly help for debugging some of the more obscure errors, and it may allow some of the error-handling to even be reduced.