Toaster dump fixes

[SK83RJOSH]

@niftools/pyffi-reviewer

Overview

Fixes three issues (primarily exceptions, and errors) that I found when attempting to use toaster on Windows 10 with Python 3.7.

Fixes Known Issues

Two exceptions in spells/nif/dump.py and adds full traces to error logging so these issues are easier to track down when submitted in future issues.

Documentation

N/A

Testing

N/A

Manual

N/A

Automated

N/A

Additional Information

I was attempting to dump the textures from Bully: Scholarship Edition when they were encountered. Be aware that I used #68 as a base for testing these changes, and I would suggest merging that PR since this verifies that it's working for at least one additional title.