[exim] How to trap "command timed out"? (avoid 451 reject)

Hi,

I'm running a command on a decoded MIME part:

${run{/path/to/command $mime_decoded_filename}}

In some very rare cases, I get "command timed out" and the message is
rejected with 451 code

Aside from debugging why it timed out, most important, how can I catch
this condition so the timed out command doesn't cause a 4xx temporary
rejection? My command not so important so I want to skip this command
and accept the message

Thanks!