unable to operate method showAndGet() in DialogWrapper

Hello,

I have a class that extends DialogWrapper

public class DraftReviewPanel extends DialogWrapper {
    private JPanel panel;
the place I am operating my class is :

private void showCreateReviewPanel(final Project project, final String diffContent, VcsRevisionNumber[] revisions, AnActionEvent e) {
    DefaultState state = ReviewDataProvider.getDefaultState(project);
    GitRepository giRepo = GitBranchUtil.getCurrentRepository(project);
    final String branch = GitBranchUtil.getBranchNameOrRev(giRepo);
    final DraftReviewPanel draftReviewPanel =
            new DraftReviewPanel(project, "Create Review Request", "", "", state.targetPeople, state.targetGroup, state.repository , branch);
    boolean test = false;
    try {
        test = draftReviewPanel.showAndGet();
    }
    catch (Exception ex)
    {
        ex.getMessage();
        ExceptionHandler.handleException(ex);
    }

I haven't oververriden the shwAndGet() function but it keeps failing on null exception :

null
java.lang.NullPointerException
 at com.intellij.ui.EditorTextFieldProviderImpl$MyEditorTextField.e(EditorTextFieldProviderImpl.java:68)
 at com.intellij.ui.EditorTextFieldProviderImpl$MyEditorTextField.createEditor(EditorTextFieldProviderImpl.java:56)
 at com.intellij.ui.EditorTextField.a(EditorTextField.java:363)
 at com.intellij.ui.EditorTextField.addNotify(EditorTextField.java:348)
 at java.awt.Container.addNotify(Container.java:2773)
 at javax.swing.JComponent.addNotify(JComponent.java:4740)
 at java.awt.Container.addNotify(Container.java:2773)
 at javax.swing.JComponent.addNotify(JComponent.java:4740)
 at java.awt.Container.addNotify(Container.java:2773)
 at javax.swing.JComponent.addNotify(JComponent.java:4740)
 at java.awt.Container.addNotify(Container.java:2773)
 at javax.swing.JComponent.addNotify(JComponent.java:4740)
 at java.awt.Container.addNotify(Container.java:2773)
 at javax.swing.JComponent.addNotify(JComponent.java:4740)
 at javax.swing.JRootPane.addNotify(JRootPane.java:757)
 at java.awt.Container.addNotify(Container.java:2773)
 at java.awt.Window.addNotify(Window.java:770)
 at java.awt.Dialog.addNotify(Dialog.java:760)
 at java.awt.Window.pack(Window.java:807)
 at com.intellij.openapi.ui.impl.DialogWrapperPeerImpl$MyDialog.show(DialogWrapperPeerImpl.java:669)
 at com.intellij.openapi.ui.impl.DialogWrapperPeerImpl.show(DialogWrapperPeerImpl.java:457)
 at com.intellij.openapi.ui.DialogWrapper.invokeShow(DialogWrapper.java:1696)
 at com.intellij.openapi.ui.DialogWrapper.show(DialogWrapper.java:1645)
 at com.intellij.openapi.ui.DialogWrapper.showAndGet(DialogWrapper.java:1660)
 at com.ritesh.idea.plugin.ui.action.ShowReviewBoard.showCreateReviewPanel(ShowReviewBoard.java:106)
 at com.ritesh.idea.plugin.ui.action.ShowReviewBoard.actionPerformed(ShowReviewBoard.java:83)
 at com.intellij.openapi.actionSystem.ex.ActionUtil$1.run(ActionUtil.java:215)
 at com.intellij.openapi.actionSystem.ex.ActionUtil.performActionDumbAware(ActionUtil.java:232)
 at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.a(ActionMenuItem.java:309)
 at com.intellij.openapi.wm.impl.FocusManagerImpl.runOnOwnContext(FocusManagerImpl.java:929)
 at com.intellij.openapi.wm.impl.IdeFocusManagerImpl.runOnOwnContext(IdeFocusManagerImpl.java:136)
 at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.actionPerformed(ActionMenuItem.java:299)
 at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
 at com.intellij.openapi.actionSystem.impl.ActionMenuItem.a(ActionMenuItem.java:116)
 at com.intellij.openapi.application.TransactionGuardImpl.a(TransactionGuardImpl.java:86)
 at com.intellij.openapi.application.TransactionGuardImpl.a(TransactionGuardImpl.java:109)
 at com.intellij.openapi.application.TransactionGuardImpl.submitTransaction(TransactionGuardImpl.java:118)
 at com.intellij.openapi.application.TransactionGuard.submitTransaction(TransactionGuard.java:122)
 at com.intellij.openapi.actionSystem.impl.ActionMenuItem.fireActionPerformed(ActionMenuItem.java:116)
 at com.intellij.ui.plaf.beg.BegMenuItemUI.a(BegMenuItemUI.java:513)
 at com.intellij.ui.plaf.beg.BegMenuItemUI.access$300(BegMenuItemUI.java:45)
 at com.intellij.ui.plaf.beg.BegMenuItemUI$MyMouseInputHandler.mouseReleased(BegMenuItemUI.java:533)
 at java.awt.Component.processMouseEvent(Component.java:6535)
 at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
 at java.awt.Component.processEvent(Component.java:6300)
 at java.awt.Container.processEvent(Container.java:2236)
 at java.awt.Component.dispatchEventImpl(Component.java:4891)
 at java.awt.Container.dispatchEventImpl(Container.java:2294)
 at java.awt.Component.dispatchEvent(Component.java:4713)
 at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
 at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
 at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
 at java.awt.Container.dispatchEventImpl(Container.java:2280)
 at java.awt.Window.dispatchEventImpl(Window.java:2750)
 at java.awt.Component.dispatchEvent(Component.java:4713)
 at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
 at java.awt.EventQueue.access$500(EventQueue.java:97)
 at java.awt.EventQueue$3.run(EventQueue.java:709)
 at java.awt.EventQueue$3.run(EventQueue.java:703)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
 at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
 at java.awt.EventQueue$4.run(EventQueue.java:731)
 at java.awt.EventQueue$4.run(EventQueue.java:729)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
 at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
 at com.intellij.ide.IdeEventQueue.k(IdeEventQueue.java:827)
 at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:651)
 at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:365)
 at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
 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)


java.lang.Throwable
 at com.intellij.openapi.diagnostic.Logger.assertTrue(Logger.java:168)
 at com.intellij.notification.Notification.<init>(Notification.java:137)
 at com.intellij.notification.Notification.<init>(Notification.java:114)
 at com.ritesh.idea.plugin.ui.ExceptionHandler$1.run(ExceptionHandler.java:80)
 at com.intellij.openapi.application.TransactionGuardImpl$2.run(TransactionGuardImpl.java:303)
 at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.a(LaterInvocator.java:410)
 at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:399)
 at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
 at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
 at java.awt.EventQueue.access$500(EventQueue.java:97)
 at java.awt.EventQueue$3.run(EventQueue.java:709)
 at java.awt.EventQueue$3.run(EventQueue.java:703)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
 at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
 at com.intellij.ide.IdeEventQueue.k(IdeEventQueue.java:827)
 at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:655)
 at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:365)
 at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
 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)


please help