UPDATE: Notice that the new version of ExtJS is now on Prototype 1.6, yeah…
In the ext-all-debug.js (version 2.0.1) I tracked the error down to line 23754. The json result being evaluated is undefined (notice that this only happens some of the time). So… after hours of head scratching and putting alerts in both the prototype library and ExtJS library to see what was wrong, it hit me…
Everything seemed to work. Now my only problem is that I now use Rails 2.0.2 with an old version of prototype. So can I use all the rails helpers?!?