finally caught an error on crash

Hello all,

Very randomly, after downloading (POP3) and reading some messages, if I  
click the button to expunge deleted messages (and this has only  
happened in the Inbox, but I have no idea if that matters) Balsa will  
just disappear.  I finally managed to get a launch icon capturing  
stderr, and got

ERROR:../balsa-git/libbalsa/mailbox_mbox.c:280:message_info_from_msgno:  
assertion failed: (msgno > 0 && msgno <= mbox->msgno_2_msg_info->len)

I haven't fully delved into the code, but I do assume the len is the  
length of the array msgno_2_msg_info (not the length of some string, as  
I first mis-assumed) which seems to be the number of messages in the  
mailbox, so could something be happening out of order during the  
expunge?  This is an mbox mailbox.

I don't really see any G_MESSAGES_DEBUG values which would be  
particularly useful.  I suppose I could run under gdb and set a  
breakpoint on that function - but this happens rarely enough that I'm  
not sure it would be worth the effort.  I suppose running under gdb  
with no breakpoints would at least let me do a backtrace if I do catch  
the crash again.

Any thoughts or suggestions?

Thanks.

Jack