Fix nil pointer panic when InputInterface is never selected

NewGameState now initialises InputInterface to the always-enabled
composite (arrow keys + keyboard + gamepad) so it is never nil.
Previously, timing out the control selection screen left InputInterface
nil, causing a panic in updateScrollIn once scroll-in completed and the
game began polling for player input.

Author: morozov

pkg/state/state.go

@@ -88,6 +88,7 @@ func NewGameState() *GameState {
 			{Lives: domain.LivesInitial},
 			{Lives: domain.LivesInitial},
 		},
+		InputInterface: input.InterfaceFor(0),
 	}
 }