XML tools assume all files have content

[polyrand]

This line of code here assumes that the file has contents (when calling s[ 0]), and breaks when that's not the case. This can be problematic when running this tool on Python projects that normally have empty __init__.py files.

Thanks for the great tool!

P.S: I know it's an easy fix and I should probably open a PR, but I would need to get familiar with nbdev first, so I'll open the issue in case it gets fixed before.