It looks like something in the patch for Bug 470430 broke Lightning 1.0pre. If you install the 20091103 build into an existing profile it fails with timezone errors on the next startup:
[calTimezoneService] using D:\dev\apps\thunderbird\extensions\firstname.lastname@example.org\timezones.sqlite
Error: No timezones found! Please install calendar-timezones.xpi.
Error: [Exception... "'<error>' when calling method: [calICalendar::uri]" nsresult: "0x804a0008 (<unknown>)" location: "JS frame :: file:///[...]/calendar-js/calCalendarManager.js :: cmgr_createCalendar :: line 613" data: no]
I think the problem might be caused by this cleanup:
> - var extMgr = Components.classes["@mozilla.org/extensions/manager;1"]
> + let extMgr = Components.classes["@mozilla.org/extensions/manager;1"]
But extMgr is later accessed outside this scope and fails.
Created attachment 409967 [details] [diff] [review]
Comment on attachment 409967 [details] [diff] [review]
Looks good. If this is not it, did you remove the stray extensions directory as noted in bug 470430?
Pushed to comm-central <http://hg.mozilla.org/comm-central/rev/1533f0738a3a>
and comm-1.9.1 <http://hg.mozilla.org/releases/comm-1.9.1/rev/520d6289316f>
(In reply to comment #3)
> If this is not it, did you remove the stray extensions directory as
> noted in bug 470430?
I did not found this directory on my system and it is not related to this bug. This bug occurs because we access undefined |extMgr| in case of Lightning, trigger an exception and fallback to the unit test section in the code linked above.
*** Bug 526419 has been marked as a duplicate of this bug. ***
Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:220.127.116.11pre) Gecko/20090915 Lightning/1.0pre Thunderbird/3.0b4... Lightning build id: 20091104034447
*** Bug 526617 has been marked as a duplicate of this bug. ***