Screen freeze and buttons unresponsive in Sandbox

The screen freezes and the user is not allowed to move or make any actions and buttons turn unresponsive if he mines down until the last block of the layer. The user is forced to shut down the game in order to break away from the freeze.

Reproduce the issue in Sandbox by mining down to the last block of the layer and observe when movement and buttons become unresponsive. Trace the freeze from that reproduction point; done means the player can move and use buttons normally without shutting down the game.

Written by the indexing model from the issue text.