Don't redirect stderr to /dev/null

`&>` redirects both `stderr` and `stdout`.
`>` redirects only stdout.

Use `&>` when we explicitly want to ignore/discard error messages,
which is rarely.

`command -v` outputs only stdout.
So, `>` is appropriate because there is expected `stderr` output.
In the rare case that command fails,
we want the reason printed.