Uncaught TypeError: Cannot read property 'on' of undefined
at Object.initialize (VM4858 PropertyGridForm.js:17)
at callMethodIfExists (sitecore.js:2817)
at LifeCycleIterator.runOn (sitecore.js:2837)
at AppManager.start (sitecore.js:2457)
at sitecore.js:418
at sitecore.js:332
at Object.execCb (require.js:1650)
at Module.check (require.js:866)
at Module.<anonymous> (require.js:1113)
at require.js:132