How can I debug a script in real-time? I need to debug an add-on in real-time (installed &amp; running in Blender).

While I am an experienced programmer in several languages, Python is not one of them.

I'm trying to fix an add-on written by someone else. Released as a Beta, the creator is no longer around to finish the job.

The add-on is active from the moment Blender starts (adding a new tab to the left margin), so placing "debugger" commands at the top of the script only crashes Blender.

Unfortunately, I can't post the code for the following reasons:


It's not mine. 
It's too big. 
It calls in-house apps to work, so you couldn't run it anyway.


I know what the problem is (it's writing to the wrong path) but not why. If only I could set breakpoints and view the contents of variables at various times, I'd be set.

Any advice is appreciated.
Run blender straight from the command line...then watch the console for the errors. If blender quits, the info will be printed out. Also, add printouts or setup a python logger to "view the contents of variables."

I can't really think of any other ways to help other than these suggestions without seeing the code (or even a description of what happens when the "bug" occurs).