Fatal error when using multiple categories per product

A fatal error was triggered by saving a sale. Here it is:

Fatal error: Uncaught TypeError: implode(): Argument #1 ($pieces) must be of type array, string given in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php:477

Stack Trace
1.	
implode(',', NULL)
\wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php:477
2.	
wsm_custom_admin_table_column('filters', 15160)
\wp-includes\class-wp-hook.php:303
3.	
WP_Hook->apply_filters('', Array)
\wp-includes\class-wp-hook.php:327
4.	
WP_Hook->do_action(Array)
\wp-includes\plugin.php:470
5.	
do_action('manage_wsm-sche...', 'filters', 15160)
\wp-admin\includes\class-wp-posts-list-table.php:1343
6.	
WP_Posts_List_Table->column_default(Object(WP_Post), 'filters')
\wp-admin\includes\class-wp-list-table.php:1452
7.	
WP_List_Table->single_row_columns(Object(WP_Post))
\wp-admin\includes\class-wp-posts-list-table.php:1377
8.	
WP_Posts_List_Table->single_row(Object(WP_Post), 0)
\wp-admin\includes\class-wp-posts-list-table.php:795
9.	
WP_Posts_List_Table->_display_rows(Array, 0)
\wp-admin\includes\class-wp-posts-list-table.php:772
10.	
WP_Posts_List_Table->display_rows()
\wp-admin\includes\class-wp-list-table.php:1364
11.	
WP_List_Table->display_rows_or_placeholder()
\wp-admin\includes\class-wp-list-table.php:1291
12.	
WP_List_Table->display()
\wp-admin\edit.php:476
13.	
{main}
thrown in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 477

Also some warnings were thrown:
Warning: foreach() argument must be of type array|object, null given in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 474
Warning: Attempt to read property "singular_name" on null in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 473
Warning: Attempt to read property "labels" on bool in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 473
Warning: Undefined array key "_wsm_tax_values_" in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 138
Warning: Undefined array key "_wsm_tax_" in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 137
Warning: Undefined array key "_wsm_type_" in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 136
Warning: Undefined array key "_wsm_tax_values_" in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 138
Warning: Undefined array key "_wsm_tax_" in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 137
Warning: Undefined array key "_wsm_type_" in \wp-content\plugins\sales-manager-for-woocommerce\includes\wsm-custom-post-type.php on line 136

It seems to me that the error happens due to the fact that I am using The SEO Framework plugin which adds a feature to select multiple categories per product.