Missing store after update: How to pinpoint

[tfd]

I upgraded a 1.2 project to 2 build 298 and it worked fine.

After upgrading my project from 2.298 to 2.341, it looks like some component might have lost its store. I get this message in firebug:

this.up("[store]") is undefined

Any suggestions on how to quickly identify which component it is? It is a fairly big project and stepping through everything seems bit rough.

[aconran]

Set break on all errors in firebug. When the debugger stops execution, examine what this is.