## Summary
This PR updates various references in the linter to compute the
line-width for summing the width of each `char` in a `str` instead of
computing the width of the `str` itself.
Refer to #12133 for more details.
fixes: #12130
## Test Plan
Add a file with null (`\0`) character which is zero-width. Run this test
case on `main` to make sure it panics and switch over to this branch to
make sure it doesn't panic now.
