Program: 190324
Project: 190324
Buggy source:
public void closeCurrentProject(){
  if (projects.hasCurrentProject()) {
    ProjectImpl currentProject=projects.getCurrentProject();
    String messageBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    String titleBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    String saveBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    String doNotSaveBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    String cancelBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    NotifyDescriptor msg=new NotifyDescriptor(messageBundle,titleBundle,NotifyDescriptor.YES_NO_CANCEL_OPTION,NotifyDescriptor.INFORMATION_MESSAGE,new Object[]{saveBundle,doNotSaveBundle,cancelBundle},saveBundle);
    Object result=DialogDisplayer.getDefault().notify(msg);
    if (result == saveBundle) {
      saveProject(currentProject);
    }
 else     if (result == cancelBundle) {
      return;
    }
    currentProject.getLookup().lookup(ProjectInformationImpl.class).close();
    projects.closeCurrentProject();
    saveProject=false;
    saveAsProject=false;
    projectProperties=false;
    closeProject=false;
    newWorkspace=false;
    deleteWorkspace=false;
    cleanWorkspace=false;
    duplicateWorkspace=false;
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        JFrame frame=(JFrame)WindowManager.getDefault().getMainWindow();
        String title=frame.getTitle();
        title=title.substring(0,title.indexOf('-') - 1);
        frame.setTitle(title);
      }
    }
);
    if (currentProject.getLookup().lookup(WorkspaceProvider.class).hasCurrentWorkspace()) {
      fireWorkspaceEvent(EventType.UNSELECT,currentProject.getLookup().lookup(WorkspaceProvider.class).getCurrentWorkspace());
    }
    for (    Workspace ws : currentProject.getLookup().lookup(WorkspaceProviderImpl.class).getWorkspaces()) {
      fireWorkspaceEvent(EventType.CLOSE,ws);
    }
    fireWorkspaceEvent(EventType.DISABLE,null);
  }
}

Fixed version (ground truth):
public boolean closeCurrentProject(){
  if (projects.hasCurrentProject()) {
    ProjectImpl currentProject=projects.getCurrentProject();
    String messageBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    String titleBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    String saveBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    String doNotSaveBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    String cancelBundle=NbBundle.getMessage(ProjectControllerImpl.class,"String_Node_Str");
    NotifyDescriptor msg=new NotifyDescriptor(messageBundle,titleBundle,NotifyDescriptor.YES_NO_CANCEL_OPTION,NotifyDescriptor.INFORMATION_MESSAGE,new Object[]{saveBundle,doNotSaveBundle,cancelBundle},saveBundle);
    Object result=DialogDisplayer.getDefault().notify(msg);
    if (result == saveBundle) {
      saveProject(currentProject);
    }
 else     if (result == cancelBundle) {
      return false;
    }
    currentProject.getLookup().lookup(ProjectInformationImpl.class).close();
    projects.closeCurrentProject();
    saveProject=false;
    saveAsProject=false;
    projectProperties=false;
    closeProject=false;
    newWorkspace=false;
    deleteWorkspace=false;
    cleanWorkspace=false;
    duplicateWorkspace=false;
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        JFrame frame=(JFrame)WindowManager.getDefault().getMainWindow();
        String title=frame.getTitle();
        title=title.substring(0,title.indexOf('-') - 1);
        frame.setTitle(title);
      }
    }
);
    if (currentProject.getLookup().lookup(WorkspaceProvider.class).hasCurrentWorkspace()) {
      fireWorkspaceEvent(EventType.UNSELECT,currentProject.getLookup().lookup(WorkspaceProvider.class).getCurrentWorkspace());
    }
    for (    Workspace ws : currentProject.getLookup().lookup(WorkspaceProviderImpl.class).getWorkspaces()) {
      fireWorkspaceEvent(EventType.CLOSE,ws);
    }
    fireWorkspaceEvent(EventType.DISABLE,null);
  }
  return true;
}