fix(main): handle ast-grep exit code 1 as non-error in run_command fu…

[khaitranhq]

Summary

Modified the run_command function in main.py to properly handle ast-grep's exit code 1, which indicates "no matches found" rather than an error condition.

Changes

Error Handling Improvement

• Changed check=True to check=False in subprocess.run() to allow manual exit code handling
• Implemented custom logic to differentiate between ast-grep's "no matches" (exit code 1) and actual errors
• Added validation for ast-grep output to determine if exit code 1 represents valid "no matches" scenarios

Exit Code 1 Handling for ast-grep

The function now recognizes exit code 1 as valid when:

• stdout is empty string, empty JSON array ([]), or starts with [ (valid JSON array)
• --json flag is not present and stdout is empty (text format with no matches)

Error Reporting

• Refactored error handling from CalledProcessError exception to explicit return code checking
• Preserved meaningful error messages with stderr output for actual failures
• Only raises RuntimeError for genuine command failures (exit codes other than 0 and ast-grep's special case 1)

Impact

This change prevents false error reporting when ast-grep returns no matches, which is a normal operational outcome rather than a failure condition. The function now correctly distinguishes between:

1. Successful execution with no matches (exit code 1 from ast-grep)
2. Successful execution with matches (exit code 0)
3. Actual command failures (other non-zero exit codes)

[HerringtonDarkholme]

thanks!

the change looks good to me