Please describe the problem:
When running the Beagle Thunderbird extension in TB 3, beta 1, a lot of warnings are generated and no mails are effectively indexed.

The warning that is generated is:
An error occurred while indexing. Error description: TypeError: hdr.folder.path is undefined


Steps to reproduce:
1. Install the Beagle extension in Thunderbird 3 beta1
2. Run
3. 


Actual results:
Errors generated, no mail indexed

Expected results:
Index all mails in Thunderbird profile

Does this happen every time?
Yes

Other information:
I have tested with TB2 and that works OK, but need to use TB3 because of some features I really need. I know TB3 is just a beta, but I hope this can be solved pro-actively, so that TB3 will get proper support. I read somewhere that the TB backend is not maintained, and that would be a great shame!