Uncaught exception: TypeError: Cannot convert 'quickgradingelement' to object

Error thrown at line 1147, column 12 in <anonymous function: error>(msg, e, src) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    throw (e || new Error(msg));

called from line 838, column 16 in <anonymous function: _notify>(callback, response, args) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    this.error('use callback error', e, args);

called from line 971, column 24 in <anonymous function: _use>(fromLoader) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    Y._notify(callback, response, args);

called via Function.prototype.call() from line 7411, column 12 in <anonymous function: _finish>(msg, success) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    onEnd.call(this.context, {

called from line 7456, column 8 in <anonymous function: _onSuccess>() in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    self._finish(msg, success);

called via Function.prototype.call() from line 7653, column 20 in <anonymous function: _insert>(d) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    fn.call(self, d);

called via Function.prototype.call() from line 7715, column 20 in <anonymous function: onSuccess>(d) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    complete.call(self, d);

called via Function.prototype.call() from line 4624, column 12 in <anonymous function: _finish>() in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    options.onSuccess.call(thisObj, data);

called from line 4806, column 12 in <anonymous function: _next>() in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    this._finish();

called from line 4913, column 8 in <anonymous function: _progress>(err, req) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    this._next();

Error initially occurred at line 143, column 8 in <anonymous function: M.mod_assign.init_grading_options>(Y) in http://fred.moodle.local/testing_master/mod/assign/module.js:

    quickgradingelement.on('change', function(e) {

called from line 836, column 16 in <anonymous function: _notify>(callback, response, args) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    callback(this, response);

called from line 817, column 16 in <anonymous function: use>(Y, response) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    Y._notify(callback, response, args);

called from line 836, column 16 in <anonymous function: _notify>(callback, response, args) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    callback(this, response);

called from line 971, column 24 in <anonymous function: _use>(fromLoader) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    Y._notify(callback, response, args);

called from line 1057, column 16 in <anonymous function: _use>(args, callback) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    handleLoader();

called from line 816, column 12 in <anonymous function: use>() in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    Y._use(args, function(Y, response) {

called from line 132, column 4 in <anonymous function: M.mod_assign.init_grading_options>(Y) in http://fred.moodle.local/testing_master/mod/assign/module.js:

    Y.use('node', function(Y) {

called from line 19, column 54 in <anonymous function>(Y) in http://fred.moodle.local/testing_master/mod/assign/view.php?action=grading&id=1079&tshow=edit:

    M.mod_assign.init_grading_options(Y);

called from line 836, column 16 in <anonymous function: _notify>(callback, response, args) in http://fred.moodle.local/testing_master/lib/yui/3.5.1/build/yui/yui.js:

    callback(this, response);