Check $localver is defined in earlier if statement to prevent undef error

Currently, line 98 (https://github.com/duckduckgo/p5-app-duckpan/blob/master/lib/App/DuckPAN/Perl.pm#L98) assumes `$localver` is defined, I've moved the check for `$localver` in the next line to the preceeding line
//cc @russellholt @malbin 
Cool! Please add a comment that explains what this line does.