$wpdb->taxonomymeta registration

In order to get the plugin working on my local installation, I had to make an ugly $wpdb hack in my functions.php (essentially duplicating what is in the Taxonomy_Metadata constructor:

if (!isset($wpdb->taxonomymeta)) {
$wpdb->taxonomymeta = $wpdb->prefix . 'taxonomymeta';
}

Since I haven’t seen anyone else having problems with this, I suspect it is something specific to my installation.

Any ideas?

https://wordpress.org/plugins/taxonomy-metadata/