Bug: Delete product leaves empty stock entries

[bitsandbots]

Describe the bug
Delete product leaves empty stock entries

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Products'
2. Click on 'delete product'
3. Go to 'Manage Stock'
4. See error

Expected behavior
Delete product should remove corresponding stock entries, or force the user to delete the stock entries before permitted to delete product.

Screenshots

Desktop (please complete the following information):

• OS: [ Windows 10 x64 ]
• Browser [ chrome ]
• Version [ 87 ]

Smartphone (please complete the following information):

Additional context

[bitsandbots]

I added a check for stock entries before allowing the user to delete the products. The user might prefer to add a stock entry containing a negative (-) quantity and note reason "destroyed, stolen, etc."