MDL-38356 Forms: Check that the form exists before applying changechecker

Signed-off-by: Andrew Robert Nicols <[email protected]>

lib/yui/formchangechecker/formchangechecker.js

@@ -21,6 +21,11 @@ YUI.add('moodle-core-formchangechecker',
                 initializer : function(config) {
                     var formid = 'form#' + this.get('formid');
 
+                    if (!currentform) {
+                        // If the form was not found, then we can't check for changes.
+                        return;
+                    }
+
                     // Add change events to the form elements
                     var currentform = Y.one(formid);
                     currentform.delegate('change', M.core_formchangechecker.set_form_changed, 'input', this);