I get this stack trace when I try to show my stage:

WARNING: Could not resolve '-fx-text-background-color' while resolving lookups for '-fx-text-fill' from rule '*.label' in stylesheet jar:file:/usr/lib/jvm/java-8-oracle/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss
Exception in Application start method
Exception in thread "main" java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:868)
at com.sun.javafx.application.LauncherImpl.access$000(LauncherImpl.java:55)
at com.sun.javafx.application.LauncherImpl$1.run(LauncherImpl.java:157)
at java.lang.Thread.run(Thread.java:724)
Caused by: java.lang.IndexOutOfBoundsException: Index: 2, Size: 2
at java.util.ArrayList.rangeCheck(ArrayList.java:638)
at java.util.ArrayList.get(ArrayList.java:414)
at com.sun.javafx.collections.ObservableListWrapper.get(ObservableListWrapper.java:87)
at com.sun.javafx.collections.VetoableListDecorator.get(VetoableListDecorator.java:265)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.impl_processCSS(Node.java:8649)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:680)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.<init>(LabeledSkinBase.java:129)
at com.sun.javafx.scene.control.skin.LabelSkin.<init>(LabelSkin.java:42)
at javafx.scene.control.Label.createDefaultSkin(Label.java:156)
at javafx.scene.control.Control.impl_processCSS(Control.java:870)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.Node.processCSS(Node.java:8604)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.impl_processCSS(Node.java:8649)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:680)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.<init>(LabeledSkinBase.java:129)
at com.sun.javafx.scene.control.skin.LabelSkin.<init>(LabelSkin.java:42)
at javafx.scene.control.Label.createDefaultSkin(Label.java:156)
at javafx.scene.control.Control.impl_processCSS(Control.java:870)
at javafx.scene.Node.processCSS(Node.java:8604)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.processCSS(Node.java:8595)
at javafx.scene.Node.impl_processCSS(Node.java:8649)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:680)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.<init>(LabeledSkinBase.java:129)
at com.sun.javafx.scene.control.skin.LabelSkin.<init>(LabelSkin.java:42)
at javafx.scene.control.Label.createDefaultSkin(Label.java:156)
at javafx.scene.control.Control.impl_processCSS(Control.java:870)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.control.Control.impl_processCSS(Control.java:866)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.control.Control.impl_processCSS(Control.java:866)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.control.Control.impl_processCSS(Control.java:866)
at javafx.scene.Node.processCSS(Node.java:8604)
at javafx.scene.Node.impl_processCSS(Node.java:8649)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:680)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.<init>(LabeledSkinBase.java:129)
at com.sun.javafx.scene.control.skin.LabelSkin.<init>(LabelSkin.java:42)
at javafx.scene.control.Label.createDefaultSkin(Label.java:156)
at javafx.scene.control.Control.impl_processCSS(Control.java:870)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.control.Control.impl_processCSS(Control.java:873)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.control.Control.impl_processCSS(Control.java:873)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.Parent.impl_processCSS(Parent.java:1228)
at javafx.scene.control.Control.impl_processCSS(Control.java:873)
at javafx.scene.Node.processCSS(Node.java:8604)
at javafx.scene.Scene.doCSSPass(Scene.java:540)
at javafx.scene.Scene.preferredSize(Scene.java:1499)
at javafx.scene.Scene.impl_preferredSize(Scene.java:1566)
at javafx.stage.Window$9.invalidated(Window.java:741)
at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:109)
at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:143)
at javafx.stage.Window.setShowing(Window.java:819)
at javafx.stage.Window.show(Window.java:834)
at javafx.stage.Stage.show(Stage.java:246)
at com.prodoko.base.client.ClientApp.start(ClientApp.java:97)
at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:811)
at com.sun.javafx.application.PlatformImpl$7.run(PlatformImpl.java:319)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:285)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:282)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:282)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
at com.sun.glass.ui.gtk.GtkApplication.access$200(GtkApplication.java:47)
at com.sun.glass.ui.gtk.GtkApplication$5$1.run(GtkApplication.java:137)
... 1 more

I have no clue whats wrong.