Use local for local variables.

### 🤔 What's the problem you've observed?

Bash support local variables, we don't use these (I think), so our state leaks.

```

#!/bin/bash

my_function () {
local func_result="some result"
echo "$func_result"
}

func_result="$(my_function)"
echo $func_result
```

From:
https://linuxize.com/post/bash-functions/