Fix this

[tumami]

Hey , i need help with this error , i dont understand

java.lang.ArrayIndexOutOfBoundsException: -1 not in range [0,2)
at edu.cmu.cs.stage3.alice.core.Behavior$Fork.getNext (Behavior.java:113)
at edu.cmu.cs.stage3.alice.core.Behavior$RuntimeStack .top(Behavior.java:55)
at edu.cmu.cs.stage3.alice.core.Behavior$RuntimeStack .pop(Behavior.java:48)
at edu.cmu.cs.stage3.alice.core.Behavior.closeFork(Be havior.java:176)
at edu.cmu.cs.stage3.alice.core.response.DoTogether$R untimeDoTogether.epilogue(DoTogether.java:85)
at edu.cmu.cs.stage3.alice.core.response.CompositeRes ponse$RuntimeCompositeResponse.childrenEpiloguesIf Necessary(CompositeResponse.java:67)
at edu.cmu.cs.stage3.alice.core.response.CompositeRes ponse$RuntimeCompositeResponse.epilogue(CompositeR esponse.java:73)
at edu.cmu.cs.stage3.alice.core.response.CompositeRes ponse$RuntimeCompositeResponse.childrenEpiloguesIf Necessary(CompositeResponse.java:67)
at edu.cmu.cs.stage3.alice.core.response.CompositeRes ponse$RuntimeCompositeResponse.epilogue(CompositeR esponse.java:73)
at edu.cmu.cs.stage3.alice.core.response.DoTogether$R untimeDoTogether.epilogue(DoTogether.java:81)
at edu.cmu.cs.stage3.alice.core.response.CompositeRes ponse$RuntimeCompositeResponse.childrenEpiloguesIf Necessary(CompositeResponse.java:67)
at edu.cmu.cs.stage3.alice.core.response.CompositeRes ponse$RuntimeCompositeResponse.epilogue(CompositeR esponse.java:73)
at edu.cmu.cs.stage3.alice.core.response.CallToUserDe finedResponse$RuntimeCallToUserDefinedResponse.epi logue(CallToUserDefinedResponse.java:94)
at edu.cmu.cs.stage3.alice.core.behavior.AbstractCond itionalBehavior.internalSchedule(AbstractCondition alBehavior.java:112)
at edu.cmu.cs.stage3.alice.core.Behavior.schedule(Beh avior.java:225)
at edu.cmu.cs.stage3.alice.core.Sandbox.scheduleBehav iors(Sandbox.java:70)
at edu.cmu.cs.stage3.alice.core.World.scheduleBehavio rs(World.java:444)
at edu.cmu.cs.stage3.alice.core.World.schedule(World. java:486)
at edu.cmu.cs.stage3.alice.core.clock.DefaultClock.sc hedule(DefaultClock.java:99)
at edu.cmu.cs.stage3.alice.authoringtool.AuthoringToo l$9.run(AuthoringTool.java:695)
at edu.cmu.cs.stage3.alice.authoringtool.util.Default Scheduler.simulateOnce(DefaultScheduler.java:115)
at edu.cmu.cs.stage3.alice.authoringtool.util.Default Scheduler.run(DefaultScheduler.java:76)
at edu.cmu.cs.stage3.scheduler.AbstractScheduler.run( AbstractScheduler.java:45)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierar chy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.Dialog$1.run(Unknown Source)
at java.awt.Dialog$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.Dialog.show(Unknown Source)
at java.awt.Component.show(Unknown Source)
at java.awt.Component.setVisible(Unknown Source)
at edu.cmu.cs.stage3.swing.DialogManager.showModalDia log(DialogManager.java:60)
at edu.cmu.cs.stage3.swing.DialogManager.showDialog(D ialogManager.java:128)
at edu.cmu.cs.stage3.alice.authoringtool.AuthoringToo l.play(AuthoringTool.java:5154)
at edu.cmu.cs.stage3.alice.authoringtool.Actions$15.a ctionPerformed(Actions.java:168)
at javax.swing.AbstractButton.fireActionPerformed(Unk nown Source)
at javax.swing.AbstractButton$Handler.actionPerformed (Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed (Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseRe leased(Unknown Source)
at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent( Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(U nknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unkno wn Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierar chy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)