fix potential overflow that can lead to infinite loop in file reading

[hellkite500]

A potential overflow bug exists in the read_file_line_counts function. Depending on system, compiler, and hardware, this can lead to a infinite loop.

Changes

• Change the i/o buffer type for character reading to int from char to avoid overflowing a possible unsigned char type.

Testing

1. Tested through ngen unit tests

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

Testing checklist

Target Environment support

• Linux (x86 and arm)
• MacOS (x86 and arm)