Game crashes after removing the button that's binded to "Tabbing Modifier"

[SomethingSomethingV2]

Here's a link to a video that shows how the crash happens just in case my wording wasn't clear: https://drive.google.com/file/d/1ap5nYbMuf7ehEqr_nRKmfU-uITtknaEV/view?usp=sharing

This is the version I was playing on:

11:35:08.262 [main] WARN  o.t.e.rendering.nui.asset.UIFormat - Field 'columnRatios' not recognized for interface org.terasology.nui.UIWidget in {"type":"RowLayout","columnRatios":0.4,"horizontalSpacing":12,"contents":[{"type":"UILabel","text":"NEO"},{"type":"UIButton","text":"${engine:menu#input-settings-apply}","id":"neo"}]}
11:35:35.348 [main] ERROR o.t.engine.core.TerasologyEngine - Uncaught exception, attempting clean game shutdown
java.lang.NullPointerException: null
        at java.base/java.util.Objects.requireNonNull(Objects.java:233)
        at java.base/java.util.Optional.of(Optional.java:113)
        at java.base/java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:194)
        at java.base/java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:191)
        at java.base/java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:150)
        at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
        at java.base/java.util.stream.ReferencePipeline.findFirst(ReferencePipeline.java:647)
        at org.terasology.engine.rendering.nui.layers.mainMenu.inputSettings.InputSettingsScreen.onClosed(InputSettingsScreen.java:306)
        at org.terasology.engine.rendering.nui.internal.NUIManagerInternal.onCloseScreen(NUIManagerInternal.java:283)
        at org.terasology.engine.rendering.nui.internal.NUIManagerInternal.closeScreen(NUIManagerInternal.java:278)
        at org.terasology.engine.rendering.nui.internal.NUIManagerInternal.popScreen(NUIManagerInternal.java:449)
        at org.terasology.engine.rendering.nui.animation.MenuAnimationSystemStub.triggerToPrev(MenuAnimationSystemStub.java:22)
        at org.terasology.engine.rendering.nui.animation.DeferredMenuAnimationSystem.triggerToPrev(DeferredMenuAnimationSystem.java:28)
        at org.terasology.engine.rendering.nui.CoreScreenLayer.triggerBackAnimation(CoreScreenLayer.java:365)
        at org.terasology.engine.rendering.nui.layers.mainMenu.inputSettings.InputSettingsScreen.lambda$initialise$4(InputSettingsScreen.java:174)
        at org.terasology.nui.ActivatableWidget.activateWidget(ActivatableWidget.java:46)
        at org.terasology.nui.widgets.UIButton.activateWidget(UIButton.java:203)
        at org.terasology.nui.widgets.UIButton$1.onMouseRelease(UIButton.java:94)
        at org.terasology.nui.canvas.CanvasImpl.processMouseRelease(CanvasImpl.java:266)
        at org.terasology.engine.rendering.nui.internal.NUIManagerInternal.mouseButtonEvent(NUIManagerInternal.java:678)
        at org.terasology.engine.rendering.nui.internal.NUIManagerInternalMethodAccess.invoke(Unknown Source)
        at org.terasology.engine.entitySystem.event.internal.EventSystemImpl$ByteCodeEventHandlerInfo.invoke(EventSystemImpl.java:399)
        at org.terasology.engine.entitySystem.event.internal.EventSystemImpl.sendConsumableEvent(EventSystemImpl.java:274)
        at org.terasology.engine.entitySystem.event.internal.EventSystemImpl.send(EventSystemImpl.java:253)
        at org.terasology.engine.core.bootstrap.eventSystem.AbstractEventSystemDecorator.send(AbstractEventSystemDecorator.java:67)
        at org.terasology.engine.network.NetworkEventSystemDecorator.send(NetworkEventSystemDecorator.java:54)
        at org.terasology.engine.core.bootstrap.eventSystem.AbstractEventSystemDecorator.send(AbstractEventSystemDecorator.java:67)
        at org.terasology.engine.recording.RecordingEventSystemDecorator.send(RecordingEventSystemDecorator.java:32)
        at org.terasology.engine.entitySystem.entity.internal.BaseEntityRef.send(BaseEntityRef.java:188)
        at org.terasology.engine.input.InputSystem.send(InputSystem.java:525)
        at org.terasology.engine.input.InputSystem.sendMouseEvent(InputSystem.java:497)
        at org.terasology.engine.input.InputSystem.processMouseButtonInput(InputSystem.java:217)
        at org.terasology.engine.input.InputSystem.processMouseInput(InputSystem.java:196)
        at org.terasology.engine.input.InputSystem.update(InputSystem.java:131)
        at org.terasology.engine.core.modes.StateMainMenu.handleInput(StateMainMenu.java:114)
        at org.terasology.engine.core.subsystem.lwjgl.LwjglInput.postUpdate(LwjglInput.java:39)
        at org.terasology.engine.core.TerasologyEngine.tick(TerasologyEngine.java:521)
        at org.terasology.engine.core.TerasologyEngine.mainLoop(TerasologyEngine.java:472)
        at org.terasology.engine.core.TerasologyEngine.runMain(TerasologyEngine.java:448)
        at org.terasology.engine.core.TerasologyEngine.run(TerasologyEngine.java:414)
        at org.terasology.engine.Terasology.call(Terasology.java:189)
        at org.terasology.engine.Terasology.call(Terasology.java:69)
        at picocli.CommandLine.executeUserObject(CommandLine.java:1933)
        at picocli.CommandLine.access$1200(CommandLine.java:145)
        at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2332)
        at picocli.CommandLine$RunLast.handle(CommandLine.java:2326)
        at picocli.CommandLine$RunLast.handle(CommandLine.java:2291)
        at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2159)
        at picocli.CommandLine.execute(CommandLine.java:2058)
        at org.terasology.engine.Terasology.main(Terasology.java:138)
11:35:35.349 [main] INFO  o.t.engine.core.TerasologyEngine - Shutting down Terasology...

[soloturn]

added the exception.

[BenjaminAmos]

Terasology/engine/src/main/java/org/terasology/engine/rendering/nui/layers/mainMenu/inputSettings/InputSettingsScreen.java

Lines 306 to 308 in 14937d2

	bindsConf.getBinds(new SimpleUri("engine:tabbingModifier")).stream().findFirst().ifPresent(input -> {
	TabbingManager.tabBackInputModifier = input;
	});

I'm going to take a guess and say that bindsConf.getBinds(new SimpleUri("engine:tabbingModifier")) returns null?

NUI has some special behaviour for the tab key which allows for tabbing through UIs. Some things may have been slightly broken when we moved the NUI code into https://github.com/MovingBlocks/TeraNUI.