If the (non-existent) Web Console isn't there then fall back to error console for content script errors

communicator/components/devtools/content/scratchpad/scratchpad.js

@@ -239,7 +239,7 @@ var Scratchpad = {
       let contentWindow = this.gBrowser.selectedBrowser.contentWindow;
 
       let scriptError = Cc["@mozilla.org/scripterror;1"].
-                        createInstance(Ci.nsIScriptError2);
+                        createInstance(Ci.nsIScriptError);
 
       scriptError.initWithWindowID(ex.message + "\n" + ex.stack, ex.fileName,
                                    "", ex.lineNumber, 0, scriptError.errorFlag,
@@ -557,10 +557,15 @@ var Scratchpad = {
    */
   openWebConsole: function SP_openWebConsole()
   {
-    if (!this.browserWindow.HUDConsoleUI.getOpenHUD()) {
-      this.browserWindow.HUDConsoleUI.toggleHUD();
+    try {
+      if (!this.browserWindow.HUDConsoleUI.getOpenHUD()) {
+        this.browserWindow.HUDConsoleUI.toggleHUD();
+      }
+      this.browserWindow.focus();
+    }
+    catch (ex) {
+      this.openErrorConsole();
     }
-    this.browserWindow.focus();
   },
 
   /**

communicator/components/devtools/moz.build

@@ -5,6 +5,6 @@
 
 EXTRA_JS_MODULES.communicator.devtools += ['modules/PropertyPanel.jsm']
 
-JS_PREFERENCE_PP_FILES += ['devtools-prefs.js']
+JS_PREFERENCE_FILES += ['devtools-prefs.js']
 
 JAR_MANIFESTS += ['jar.mn']