Blank error pop-up when adding item with non-percent discount to cart

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.1.0
• Fix Version/s: 2.1.1
• Component/s: Digital Merchandise Management → Discounts, Shopping Experience → Widgets
• Labels:
  • backend
• Git Pull Request: https://github.com/marco-leo/liferay-portal-ee/pull/751

When adding an item (with non-percent discount applied) to the cart, a blank error message appears.

Assumptions

1. Products w/ available inventory are present in the catalog.
2. User has permission to add items to cart.
3. Non-percent discount is configured. 
4. At least one of the available products in the catalog has the discount applied to it.

Steps to Reproduce

1. Go to catalog.
2. Find product with non-percent discount applied.
   1. 
3. Click Add to Cart.

Expected Result

 Item is added to the cart without error.

 User is able to add other products to the cart after that without any error.

Actual Result

 Item is added to the cart.

 A blank error message appears.

 A blank error message appears again when adding other products (with or without discount) to the cart after that.

Reproduced on

Tomcat 9.0.6 + MySQL 5.7

Portal 7.1.10 GA1 fix pack 17 

Commerce 2.1 RC 6