Issue 3431 - Element Hiding Helper shutdown fails (shutdown is not a function)

chrome/content/frameScript.js

 /*
  * This Source Code is subject to the terms of the Mozilla Public License
  * version 2.0 (the "License"). You can obtain a copy of the License at
  * http://mozilla.org/MPL/2.0/.
  */
 
 (function()
 {
   const Cu = Components.utils;
 
   let rand = Components.stack.filename.replace(/.*\?/, "");
   let module = "chrome://elemhidehelper/content/actor.jsm?" + rand;
   let {shutdown, getNodeInfo, togglePreview, forgetNode} = Cu.import(module, {});
 
   addMessageListener("ElemHideHelper:Shutdown", onShutdown);
   addMessageListener("ElemHideHelper:GetNodeInfo", onGetNodeInfo);
   addMessageListener("ElemHideHelper:Preview", onTogglePreview);
 
   function onShutdown()
   {
     shutdown();
-    Cu.unload(module);
+    try
+    {
+      Cu.unload(module);
+    }
+    catch (e)
+    {
+      Cu.reportError(e);
+    }
+
     removeMessageListener("ElemHideHelper:Shutdown", onShutdown);
     removeMessageListener("ElemHideHelper:GetNodeInfo", onGetNodeInfo);
     removeMessageListener("ElemHideHelper:Preview", onTogglePreview);
   }
 
   function onGetNodeInfo(message)
   {
     let nodeInfo = getNodeInfo(message.objects.element);
     nodeInfo.messageId = message.data;
     sendAsyncMessage("ElemHideHelper:GetNodeInfo:Response", nodeInfo);
   }
 
   function onTogglePreview(message)
   {
     togglePreview(message.data.nodeID, message.data.stylesheetData);
     if (message.data.forgetNode)
       forgetNode(message.data.nodeID);
   }
 })();