TL;DR: if ggshield 1.51.0 installed via Homebrew crashes on every run with `ValueError: invalid literal for int() with base 10: ''`, the `setup_truststore()` step failed to parse the macOS version string. Run `brew upgrade ggshield` to get 1.52.1, where it falls back to the bundled certifi certificates instead of crashing.

```text
ValueError: invalid literal for int() with base 10: ''
```

## Steps

1. Upgrade:

```sh
brew upgrade ggshield
```

   Expected: ggshield 1.52.1+.

2. Re-run your scan.

   Expected: no more startup crash. Success check: the scan completes normally.

## When to use this

- ggshield 1.51.0 via Homebrew on macOS, every run crashes at startup before scanning.

## When NOT to use this

- Scans fail after starting; that is a different problem.
- Non-macOS installs; the version-string parsing is macOS-specific.

## Compatibility

- ggshield 1.52.1+.

## Variant phrasings

- "ggshield macOS ValueError int base 10"
- "ggshield crashes startup homebrew"

## Root cause

`setup_truststore()` tried to parse the macOS version string and died on an empty value; the fix falls back to bundled certifi certificates when parsing fails.

## Edge cases

- None; the fallback covers unparseable version strings generally.