diff --git a/lib/form/yui/shortforms/shortforms.js b/lib/form/yui/shortforms/shortforms.js
index c874791f3f0..a14746dca11 100644
--- a/lib/form/yui/shortforms/shortforms.js
+++ b/lib/form/yui/shortforms/shortforms.js
@@ -84,7 +84,12 @@ YUI.add('moodle-form-shortforms', function(Y) {
             fieldset.toggleClass(CSS.COLLAPSED);
             // Get corresponding hidden variable
             // - and invert it.
-            var statuselement = new Y.one('input[name=mform_isexpanded_'+fieldset.get('id')+']');
+            var statuselement = Y.one('input[name=mform_isexpanded_'+fieldset.get('id')+']');
+            if (!statuselement) {
+                Y.log("M.form.shortforms::switch_state was called on an fieldset without a status field: '" +
+                    fieldset.get('id') + "'", 'debug');
+                return;
+            }
             statuselement.set('value', Math.abs(Number(statuselement.get('value'))-1));
         }
     });
diff --git a/lib/form/yui/showadvanced/showadvanced.js b/lib/form/yui/showadvanced/showadvanced.js
index 562e20e6bcd..f43e48f274a 100644
--- a/lib/form/yui/showadvanced/showadvanced.js
+++ b/lib/form/yui/showadvanced/showadvanced.js
@@ -67,7 +67,12 @@ YUI.add('moodle-form-showadvanced', function(Y) {
             Y.one('#'+this.get('formid')).delegate('click', this.switch_state, SELECTORS.FIELDSETCONTAINSADVANCED+' .'+CSS.MORELESSTOGGLER);
         },
         process_fieldset : function(fieldset) {
-            var statuselement = new Y.one('input[name=mform_showmore_'+fieldset.get('id')+']');
+            var statuselement = Y.one('input[name=mform_showmore_'+fieldset.get('id')+']');
+            if (!statuselement) {
+                Y.log("M.form.showadvanced::process_fieldset was called on an fieldset without a status field: '" +
+                    fieldset.get('id') + "'", 'debug');
+                return;
+            }
             var morelesslink = Y.Node.create('<a href="#"></a>');
             morelesslink.addClass(CSS.MORELESSTOGGLER);
             if (statuselement.get('value') === '0') {
diff --git a/lib/outputrequirementslib.php b/lib/outputrequirementslib.php
index 89d509f2fd9..484ac3c8293 100644
--- a/lib/outputrequirementslib.php
+++ b/lib/outputrequirementslib.php
@@ -155,12 +155,15 @@ class page_requirements_manager {
         $sep = empty($CFG->yuislasharguments) ? '?' : '/';
 
         $this->yui3loader = new stdClass();
+        $this->YUI_config = new stdClass();
 
         // Set up some loader options.
         if (debugging('', DEBUG_DEVELOPER)) {
             $this->yui3loader->filter = 'RAW'; // For more detailed logging info use 'DEBUG' here.
+            $this->YUI_config->debug = true;
         } else {
             $this->yui3loader->filter = null;
+            $this->YUI_config->debug = false;
         }
         if (!empty($CFG->useexternalyui) and strpos($CFG->httpswwwroot, 'https:') !== 0) {
             $this->yui3loader->base = 'http://yui.yahooapis.com/' . $CFG->yui3version . '/build/';
@@ -182,7 +185,6 @@ class page_requirements_manager {
         }
 
         // Set up JS YUI loader helper object.
-        $this->YUI_config = new stdClass();
         $this->YUI_config->base         = $this->yui3loader->base;
         $this->YUI_config->comboBase    = $this->yui3loader->comboBase;
         $this->YUI_config->combine      = $this->yui3loader->combine;