Function extract_new_lnum_value 

fn extract_new_lnum_value(lnum_line: &str) -> Result<usize>

Extracts the line number from a git diff hunk header line.

Errors

• If the hunk header line lacks sufficient space-separated parts.
• If the newline number part is malformed (missing comma).
• If the extracted line number value cannot be parsed as a valid usize.