contributeMarkupRenderer missing JavaScriptSupport

[Michael Wyraz]

Hi,

we have a layout package that adds some extra css/js to all pages. It is 
implemented as contributeMarkupRenderer:

        public void
   contributeMarkupRenderer(OrderedConfiguration<MarkupRendererFilter>
   configuration, final Environment environment)
        {
            MarkupRendererFilter importUIStack = new MarkupRendererFilter()
            {
                public void renderMarkup(MarkupWriter writer,
   MarkupRenderer renderer)
                {
                    renderer.renderMarkup(writer);

                    JavaScriptSupport
   jss=environment.peekRequired(JavaScriptSupport.class);
                    jss.importStack("ui");
                }
            };
            configuration.add("ImportUIStack", importUIStack);
        }

We run Tapestry 5.4-beta3. The problem is that randomly after 
application start JavaScriptSupport is not set on environment. If this 
happens, we must restart the apllication to get it work again.

Does anyone have an idea what the problem might be?

Kind regards,
Michael.