Digger sometimes generate room with one cell

[jcubic]

I have basic gold collecting game https://codepen.io/jcubic/pen/ejJvdW?editors=0010

and it sometimes generate map that look like this:

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#@#
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You can test this by calling Game._generateLevel('>'); Game.player._draw() few times from console.

[jcubic]

Sorry it seems that there is bug in my code user is out of the map.