Error handling for Script Task

I'm importing an Excel file and massaging it with a custom script task. I get an error "Index was outside the bounds of the array." That error is helpful but I needed to know which of the 70,000+ lines the error occurred on. What is the best way of devbugging this issue? Try-Catch-Finally with messageboxes in the Catch clause?

Barkingdog

Assuming this is Script Task, not Script Dataflow Component, you can set a breakpoint at the beggining of the task, then use menu Debug > Exceptions, check the 'Thrown' box - this will make IDE stop when an exception is thrown by the Script Task.

P.S. 70,000+ lines seems to be way too much for script task. You may find a custom task to be a better option for such undertaking.