Error causing site unavailable with latest Showcase and Widget Framework

I have Showcase 1.3.1 and installed latest Widget Framework 2.4.6d, on XF 1.2.3 for my DEV site. After upgrading WidgetFramework, I now get the following error across the whole site ...

Code:

An exception occurred: Undefined index: attachments in XF/library/NFLJ/Showcase/WidgetRenderer/TabbedItems.php on line 64
XenForo_Application::handlePhpError() in NFLJ/Showcase/WidgetRenderer/TabbedItems.php at line 64
NFLJ_Showcase_WidgetRenderer_TabbedItems->_render() in WidgetFramework/WidgetRenderer.php at line 668
WidgetFramework_WidgetRenderer->render() in WidgetFramework/Core.php at line 356
WidgetFramework_Core->_renderWidgetsFor() in WidgetFramework/Core.php at line 273
WidgetFramework_Core->renderWidgetsFor() in WidgetFramework/Listener.php at line 126
WidgetFramework_Listener::template_post_render()
call_user_func_array() in XenForo/CodeEvent.php at line 58
XenForo_CodeEvent::fire() in XenForo/Template/Abstract.php at line 195
XenForo_Template_Abstract->render() in XenForo/Template/Public.php at line 110
XenForo_Template_Public->render() in XenForo/ViewRenderer/HtmlPublic.php at line 119
XenForo_ViewRenderer_HtmlPublic->renderContainer() in XenForo/FrontController.php at line 604
XenForo_FrontController->renderView() in XenForo/FrontController.php at line 158
XenForo_FrontController->run() in /XF/index.php at line 13

PHP 5.5.8-1~dotdeb.1 (cli) (built: Jan 12 2014 02:22:36)
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2013 Zend Technologies
with Zend OPcache v7.0.3-dev, Copyright (c) 1999-2013, by Zend Technologies

It appears if I do a browser forced refresh (CTRL|CMD - R), then it will sometimes work.

 

Thanks. Tried that, but hasn't worked for me. Even tried disabling WidgetFramework add-on entirely, loading site pages, then re-enabling WidgetFramework again, and then enabling the Showcase block. Unfortunately, still get the error.
I've disabled the block for now.

 

That appears to have fixed it. I had that option un-ticked (not showing thumbnails for my widget), so ticked it and refreshed a few site pages, then un-ticked it again.
Not getting the error anymore.
Thanks Bob!