my $path = pathIsInsidePrefix($path, $Nix::Config::storeDir);
    error($c, "Build product refers outside of the Nix store.") unless defined $path;
    return $path;

    my $p = pathIsInsidePrefix($path, $Nix::Config::storeDir);
    error($c, "Build product refers outside of the Nix store.") unless defined $p;
    return $p;