Error Traceback

It downloaded all the mail (100%), and then started showing the following error:
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Thanks! (gmb.py revision 691):
Traceback (most recent call last):
File "gmb.pyo", line 1138, in iterMails
File "gmb.pyo", line 679, in fetchMessageId
File "gmb.pyo", line 689, in fetchMessage
TypeError: 'NoneType' object is unsubscriptable
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It repeated the error like 5-6 times, and then continued with the backup of labels. As far as I can tell everything worked fine.

Thanks for the application and I hope this info helps making it better...