ExtJs 4.2.0 - Application works using ext-debug.js but fails using ext.js
I'm in a very strange situation, when I use ext-debug.js in my index.jsp file, my application works fine, but when I try to use the minified version of ext-debug.js which is ext.js, my application fails, I'm getting an "Uncaught TypeError: Cannot call method substring of undefined". The problem appears in the method that parses the namespace of the class I want to instantiate. But why this method works fine on the unminified version of extjs? And more importantly what should I do to fix the error? Any ideas? How should I debug this since it appears only in the minified version?