There's a crash when you have nothing in the current slot, but attempt to place it on a ship in build mode.
java.lang.NullPointerException: Exception: REQUESTED TYPE 0 IS NULL at org.schema.game.common.data.element.ElementKeyMap.getInfo(ElementKeyMap.java:635) at org.schema.game.client.controller.manager.ingame.PlayerInteractionControlManager.buildBlock(PlayerInteractionControlManager.java:197) at org.schema.game.client.controller.manager.ingame.SegmentBuildController.buildButtonPressed(SegmentBuildController.java:426) at org.schema.game.client.controller.manager.ingame.SegmentBuildController.handleMouseEvent(SegmentBuildController.java:379) at org.schema.game.client.controller.manager.AbstractControlManager.handleMouseEvent(AbstractControlManager.java:281) at org.schema.game.client.controller.manager.ingame.ship.ShipControllerManager.handleMouseEvent(ShipControllerManager.java:89) at org.schema.game.client.controller.manager.AbstractControlManager.handleMouseEvent(AbstractControlManager.java:281) at org.schema.game.client.controller.manager.AbstractControlManager.handleMouseEvent(AbstractControlManager.java:281) at org.schema.game.client.controller.manager.ingame.PlayerInteractionControlManager.handleMouseEvent(PlayerInteractionControlManager.java:1256) at org.schema.game.client.controller.manager.AbstractControlManager.handleMouseEvent(AbstractControlManager.java:281) at org.schema.game.client.controller.manager.AbstractControlManager.handleMouseEvent(AbstractControlManager.java:281) at org.schema.game.client.controller.manager.ingame.InGameControlManager.handleMouseEvent(InGameControlManager.java:319) at org.schema.game.client.controller.manager.AbstractControlManager.handleMouseEvent(AbstractControlManager.java:281) at org.schema.game.client.controller.manager.GlobalGameControlManager.handleMouseEvent(GlobalGameControlManager.java:249) at org.schema.game.client.controller.GameClientController.updateInput(GameClientController.java:3255) at org.schema.game.client.controller.GameClientController.updateStateInput(GameClientController.java:3014) at org.schema.schine.graphicsengine.core.GLFrame.start(GLFrame.java:1014) at org.schema.schine.graphicsengine.core.GLFrame.startGraphics(GLFrame.java:1181) at org.schema.game.client.controller.GameClientController.startGraphics(GameClientController.java:2329) at org.schema.game.common.ClientRunnable.run(ClientRunnable.java:86) at java.lang.Thread.run(Thread.java:662)