Destroyed food market obviously has no product assigned

Issue description

Very minor issue. Food market about to be destroyed sends message it has no product assigned.

Reproduction steps

1. Empty food from food market
2. Select food market, hit delete
3. While waiting for the trucks to actually demolish the food market, a warning shows that this market has no product assigned.
4. Obviously.

Game version and build number

v0.6.4d b347

Operating system

Windows

This was fixed in one of our previous updates. Thanks for reporting it!