java.lang.NullPointerException
        at org.netbeans.modules.java.source.classpath.CacheClassPath.<init>(CacheClassPath.java:85)
        at org.netbeans.modules.java.source.classpath.CacheClassPath.forClassPath(CacheClassPath.java:192)
        at org.netbeans.api.java.source.ClasspathInfo.<init>(ClasspathInfo.java:112)
        at org.netbeans.api.java.source.ClasspathInfo.create(ClasspathInfo.java:192)
        at org.netbeans.modules.java.j2seproject.J2SEProjectUtil.isMainClass(J2SEProjectUtil.java:118)
        at org.netbeans.modules.java.j2seproject.J2SEActionProvider.isSetMainClass(J2SEActionProvider.java:910)
        at org.netbeans.modules.java.j2seproject.J2SEActionProvider.getTargetNames(J2SEActionProvider.java:436)
        at org.netbeans.modules.java.j2seproject.J2SEActionProvider$3.run(J2SEActionProvider.java:318)
        at org.netbeans.api.java.source.ui.ScanDialog.runWhenScanFinished(ScanDialog.java:150)
        at org.netbeans.modules.java.j2seproject.J2SEActionProvider.invokeAction(J2SEActionProvider.java:356)
        at org.netbeans.modules.debugger.jpda.projects.StepIntoActionProvider.invokeAction(StepIntoActionProvider.java:118)
        at org.netbeans.modules.debugger.jpda.projects.StepIntoActionProvider.postAction(StepIntoActionProvider.java:113)
        at org.netbeans.api.debugger.ActionsManager.postAction(ActionsManager.java:230)
        at org.netbeans.modules.debugger.ui.actions.DebuggerAction.actionPerformed(DebuggerAction.java:99)
        at org.openide.windows.TopComponent.processKeyBinding(TopComponent.java:971)
        at javax.swing.JComponent.processKeyBindings(JComponent.java:2818)
        at javax.swing.JComponent.processKeyEvent(JComponent.java:2735)
        at java.awt.Component.processEvent(Component.java:5379)
        at java.awt.Container.processEvent(Container.java:2010)
        at java.awt.Component.dispatchEventImpl(Component.java:4068)
        at java.awt.Container.dispatchEventImpl(Container.java:2068)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1826)
        at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:681)
        at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:938)
        at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:810)
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:645)
        at java.awt.Component.dispatchEventImpl(Component.java:3941)
        at java.awt.Container.dispatchEventImpl(Container.java:2068)
        at java.awt.Window.dispatchEventImpl(Window.java:1791)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)