The situation:

After installing ggshield 1.51.0 via Homebrew on macOS, every run crashes at startup with ValueError: invalid literal for int() with base 10: ''. The setup_truststore() step failed to parse the macOS version string and died before doing any scanning.

What actually fixes it (verified in the thread):

Fixed in ggshield 1.52.1, where setup_truststore() falls back to the bundled certifi certificates when the macOS version cannot be parsed instead of crashing. Run brew upgrade ggshield to get it. The reporter confirmed the fix works.