I used a perk point to get extra skill points, applied them, and then undid the perk that awards skill points and crashed the game. Should have known better.
java.lang.NullPointerException
 at com.majalis.scenes.SkillSelectionScene.handleNegativeSkillPoints(SkillSelectionScene.java:550)
 at com.majalis.scenes.SkillSelectionScene.access$5700(SkillSelectionScene.java:41)
 at com.majalis.scenes.SkillSelectionScene$PerkDisplay$2.clicked(SkillSelectionScene.java:922)
 at com.badlogic.gdx.scenes.scene2d.utils.ClickListener.touchUp(ClickListener.java:88)
 at com.badlogic.gdx.scenes.scene2d.InputListener.handle(InputListener.java:59)
 at com.badlogic.gdx.scenes.scene2d.Stage.touchUp(Stage.java:351)
 at com.badlogic.gdx.backends.lwjgl.LwjglInput.processEvents(LwjglInput.java:360)
 at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:221)
 at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:128)