Hard to recreate errors

[RyanGrieb]

The following are errors thrown that are hard to re-create

When the game starts, this error is rarely thrown:

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "com.badlogic.gdx.scenes.scene2d.Actor.parentToLocalCoordinates(com.badlogic.gdx.math.Vector2)" because "child" is null
	at com.badlogic.gdx.scenes.scene2d.Group.hit(Group.java:249)
	at com.badlogic.gdx.scenes.scene2d.Group.hit(Group.java:250)
	at com.badlogic.gdx.scenes.scene2d.Stage.hit(Stage.java:729)
	at com.badlogic.gdx.scenes.scene2d.Stage.mouseMoved(Stage.java:381)
	at com.badlogic.gdx.InputMultiplexer.mouseMoved(InputMultiplexer.java:146)
	at com.badlogic.gdx.InputEventQueue.drain(InputEventQueue.java:76)
	at com.badlogic.gdx.backends.lwjgl3.DefaultLwjgl3Input.update(DefaultLwjgl3Input.java:189)
	at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Window.update(Lwjgl3Window.java:394)
	at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.loop(Lwjgl3Application.java:143)
	at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.<init>(Lwjgl3Application.java:116)
	at me.rhin.openciv.lwjgl3.Lwjgl3Launcher.createApplication(Lwjgl3Launcher.java:25)
	at me.rhin.openciv.lwjgl3.Lwjgl3Launcher.main(Lwjgl3Launcher.java:18)```

I think it has something to do w/ RelativeMouseMoveEvent and Units being added on a different thread than libgdx


When city state's move around (And move into & attack)?
The server attempts to move dead city state units.