Bed linen sets

Error message

• Notice: Undefined index: product_id in custom_module_form_alter() (line 1165 of /home/houserac/public_html/sites/all/modules/custom/custom_module/custom_module.module).
• Notice: Undefined index: product_id in custom_module_form_alter() (line 1165 of /home/houserac/public_html/sites/all/modules/custom/custom_module/custom_module.module).