How to reproduce problem:
Create a Sencha Touch project, drag an array store, save, close designer. When opening designer again if you click on the project name from the startup splash screen the load will fail with the following error:
TypeError: 'undefined' is not an object
I have done some trial and error and discovered that if you open the project from the spash screen or by double clicking the project file you get this error. However, if you create a new project, and then select File > Open Project, it will open just fine.
I believe a coworker of mine has already reported this but I wanted to give some more details on how I was able to get the project open.
I'm having the same issue. My env. is OS X 10.6.8, Designer 2. build 82. I read in a different thread there was a new release coming soon that should address this issue. Looking forward to the updated version