fix(search): fail out on no package

[Elsie19]

Purpose

Currently search.sh uses return instead of exit to signify a non existent package, but that doesn't work, which gives an exit code of zero instead of one.

Approach

Replace certain returns with exits

Checklist

• I confirm that I have read the contributing guidelines, and this pull request is abiding by all the clauses stated in the guideline.

[wizard-28]

I think we've discussed this 2 times prior, and I seem to have forgotten why we went with return.

[Elsie19]

return is used for functions to give a return value, and exit exits a script. A return will do nothing if not in a function, which this PR fixes, by changing the offending returns to exits, so pacstall errors out with the correct exit code

[wizard-28]

@henryws this is going stale.

[Elsie19]

Give me one more week to finish this PR.

[Elsie19]

@wizard-28 ready.