Products prices show as $0.00 / $NaN in cart if all available prices removed after product added to cart

[rbarreca]

Describe the bug
If a buyer adds a product to her cart, then market manager removes all prices for that product, then buyer refreshes /cart she will see all products show as $0.00 / $NaN.

To Reproduce
Steps to reproduce the behavior:

1. Add a product to cart and click Checkout
2. Notice product has the correct price
3. As a market manager, go to that product's Prices tab and delete all prices
4. Refresh /cart page as the buyer
5. Notice product prices showing up as $0.00 / $NaN

Expected behavior
Would expect an error message showing #{product.name} no longer available for purchase and a Rollbar.info to go out letting us know this happened (for further debugging/product improvements).

Screenshots

Additional context
There seems to be more ways to repro this and more ramifications of this that are TBD.

User reports

• https://localorbit.zendesk.com/agent/tickets/14427
• https://localorbit.zendesk.com/agent/tickets/14434