-my $part_pkg = FS::part_pkg->by_key($pkgpart);
-my %pkg_options = $part_pkg->options;
-$pkg_options{'usage_taxproductnum_'} = $part_pkg->taxproductnum;
+my %pkg_options;
+if ($pkgpart) {
+ my $part_pkg = FS::part_pkg->by_key($pkgpart);
+ %pkg_options = $part_pkg->options;
+ $pkg_options{'usage_taxproductnum_'} = $part_pkg->taxproductnum;
+}