Finding a few bugs on 15.3.e with Fork solitaire.
Firstly, I can get softlocked if I pick up a stack without a valid place to move it to.
Also, the game crashes sometimes when I detach a fork. I'm not sure of the exact condition of the game when it happened, but it's happened twice in a row now:
```
Error
modules/fork_data.lua:430: attempt to index a nil value
Traceback
[love "callbacks.lua"]:228: in function 'handler'
modules/fork_data.lua:430: in function 'pick_card'
modules/fork_data.lua:220: in function 'mouse_left'
input.lua:171: in function <input.lua:169>
inputsystem.lua:16: in function 'input'
inputsystem.lua:153: in function <inputsystem.lua:146>
[love "callbacks.lua"]:154: in function <[love "callbacks.lua"]:144>
[C]: in function 'xpcall'
```