Sprint Preview Issue Rewrites Pane Content Instead of Adding New Tabbed Pane.

[JC-ProgJava]

• Open re-writes tabbed pane instead of adds for named files.

         Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
            at Frame.saveFile(SmartEditor.java:594)
            at Frame.lambda$createFrame$11(SmartEditor.java:331)
            at Frame$$Lambda$43/0000000000000000.actionPerformed(Unknown Source)
            at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
            at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
            at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
            at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
            at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
            at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:842)
            at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:886)
            at java.awt.Component.processMouseEvent(Component.java:6539)
            at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
            at java.awt.Component.processEvent(Component.java:6304)
            at java.awt.Container.processEvent(Container.java:2239)
            at java.awt.Component.dispatchEventImpl(Component.java:4889)
            at java.awt.Container.dispatchEventImpl(Container.java:2297)
            at java.awt.Component.dispatchEvent(Component.java:4711)
            at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
            at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4535)
            at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
            at java.awt.Container.dispatchEventImpl(Container.java:2283)
            at java.awt.Window.dispatchEventImpl(Window.java:2746)
            at java.awt.Component.dispatchEvent(Component.java:4711)
            at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
            at java.awt.EventQueue.access$500(EventQueue.java:97)
            at java.awt.EventQueue$3.run(EventQueue.java:709)
            at java.awt.EventQueue$3.run(EventQueue.java:703)
            at java.security.AccessController.doPrivileged(AccessController.java:704)
            at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
            at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
            at java.awt.EventQueue$4.run(EventQueue.java:733)
            at java.awt.EventQueue$4.run(EventQueue.java:731)
            at java.security.AccessController.doPrivileged(AccessController.java:704)
            at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
            at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
            at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
            at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
            at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
            at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
            at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
            at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)