ace:tree and empty list model value.

Hello,

This seems also related to the issue http://www.icesoft.org/JForum/posts/list/0/23494.page#81859 .

The tree component crashes if it is used inside a component and get's an empty list as model.
Ok, this may be a problem of the application programmer at first glance.

However, if the ace:tree is guarded by
Code:

  <ui:fragment rendered="#{not empty model}">
      <ace:tree value="#{model}"/>
 </ui:fragment>

it still crashed with
Code:

 SCHWERWIEGEND: java.lang.IllegalArgumentException: Navigating to first root of empty model.
 	at org.icefaces.ace.model.tree.ListNodeDataModel.navToKey(ListNodeDataModel.java:88)
 	at org.icefaces.ace.model.tree.ListNodeDataModel.navToKey(ListNodeDataModel.java:24)
 	at org.icefaces.ace.component.tree.Tree.setNodeToKey(Tree.java:159)
 	at org.icefaces.ace.component.tree.Tree.invokeOnComponent(Tree.java:996)
      ...