Fix error when collection is not found

src/pfwbged/collection/portlet.pt

@@ -14,7 +14,8 @@
         <span class="portletTopRight"></span>
     </dt>
 
-    <dd class="portletItem" tal:define="table python: view.table()">
+    <dd class="portletItem" tal:define="table python: view.table()"
+                            tal:condition="table">
       <div tal:attributes="class python: table.__class__.__name__"
            tal:content="structure python: table.render()">
       </div>

src/pfwbged/collection/portlet.py

@@ -152,7 +152,10 @@ class Renderer(base.Renderer):
         return result
 
     def table(self):
-        table_class = get_appropriate_table_class(self.context, self.collection().query)
+        collection = self.collection()
+        if collection is None:
+            return
+        table_class = get_appropriate_table_class(self.context, collection.query)
         table = table_class(self, self.request)
         table.values = self.results()
         table.update()