When combining stacks, one of the stacks can disappear

[davidmfinol]

Describe the bug
Per jeffrobot on Discord:
Sometimes when I'm trying to put one stack of cards onto a second stack of cards to combine them, one of the stacks will disappear completely.

Expected behavior
Stacks should never disappear.

Additional context
I had another stack destruction tonight, and it was the bottom stack that disappeared. The one I was moving persisted.