I'm not sure if anyone can help? I've been trying to solve this problem for some time and I've narrowed it down.
I am currently having a problem when disabling a product in Magento 2. When I disable a product I get the following error
Notice: Undefined index: quantity in /home/customer/www/domain.co.uk/public_html/vendor/magento/module-inventory-sales/Model/GetProductSalableQty.php on line 83
This when brings up the following Screenshot in Catalog view https://pasteboard.co/Jhs7D2g.png
For a temporary fix, I can log in to the database and change the SKU in catalog_product_entity table. Just by adding a random number on the end.
But if I then edit the SKU and remove the random digit and enable the product this fixes the problem until I disable it again.
Tldr: When a product is disabled this shows the above error