Bug Description:

"Fatal error: Uncaught WC_Data_Exception:" is displayed when user tries to allow backorders with edit bulk action on products including with "Affliated/External Product" on "All Products" Page

Environment:

Woocommerce Version : WooCommerce 5.2.2 and 5.1
WordPress version: (v5.7)

PC:
Windows 10, Mac 10.14.6
Chrome(Version 89.0.4389.90)
Firefox(Version 87.0)
Safari: v13.1.1

Steps To Reproduce:

1. Create any test site using JN site.
2. Install and activate all the required plugins
3. Complete OBW setup
4. Go to Products->Import and import "sample_products.csv"
5. Go to All Products, once all the products are imported
6. Click on "Bulk Actions" dropdown and Select "Edit" , select all products by ticking on check box below it
7. Click on "Apply" button
8. Click on "Backorders?" dropdown and Select any one of the Allow options
9. Click on "Update" button
10. Observe that "Fatal error: Uncaught WC_Data_Exception:" is displayed when user tries to allow backorders with edit bulk action on products including with "Affliated/External Product" on "All Products" Page

Actual Result:

"Fatal error: Uncaught WC_Data_Exception:" is displayed when user tries to allow backorders with edit bulk action on products including with "Affliated/External Product" on "All Products" Page

Expected Result:

Proper validation should be displayed when user tries to allow backorders with edit bulk action on products including with "Affliated/External Product" on "All Products" Page or it should exclude "Affliated/External Product when bulk product edit action is applied

Video:

Isolating the problem (mark completed items with an [x]):

• I have deactivated other plugins and confirmed this bug occurs when only WooCommerce plugin is active.
• This bug happens with a default WordPress theme active, or Storefront.
• I can reproduce this bug consistently using the steps above.