Initialize file descriptors to None before opening to prevent
UnboundLocalError in the finally block if file opening fails.
Changes:
- Initialize fin = None and fout = None at function start
- Check if descriptors are not None before closing
- Remove UnboundLocalError from exception handling (no longer needed)
This improves code quality by eliminating the need to catch an error
that indicates a logic bug. The existing tests verify correct behavior.
Fixes#6
Maks Snegov
5dc9235992