Inline entity not working with entity reference(product variation) field in custom content type.

I am using drupal commerce module and I don't want to use product entity provided by drupal commerce module. So create a content type with Reference field (product variation) and select "inline entity form - Complex" in Manage form display.
when I creating the node with variation I got an error

"Fatal error: Call to a member function toUrl() on null in C:\xampp\htdocs\example-module\modules\contrib\commerce\modules\product\commerce_product.module on line 143"