Exit with a status code greather than 0 when the `--local` flag is used but no data is found

[edubxb]

Would be nice if awless will return an exit code greater than 0 when the --local flag is used but no data is found, p.e.:

awsless show --local <instance id>

so will be easy to check if the command returns no data when is used in scripts.

Currently the only way is redirecting the stderr to /dev/null and then check if there's no output in stdout.

IMHO checking status code is more elegant.

[simcap]

Consistent code status is paramount! Thanks for spotting this one. We will fix that.

[edubxb]

Works, thanks!