This solution solved it for us
I got the same.. And I fixed it
I am new to extJs. I also got the same error message Undefined is not an Object. When I checked in detail the xtype I gave was incorrect. I believe this error occurs when U gave an incorrect xtype.
Often, The Error Can Be Ignored
I have found that the error is produced when I use a static html file vs one served from http:// But the jsb3 file is fine.
I get the error from this command:
sencha create jsb -a index.html -p app.jsb3
But not this command using http://:
sencha create jsb -a http://localhost:9090/app/index.html -p app.jsb3
But in both cases, the jsb3 file is fine. I didn't realize this at first...I assumed the error caused a failure to build the file.