Caught Exception TypeError: old is null

[bfry25]

getting the following repeatedly:
Caught Exception TypeError: old is null
aspect@chrome://awsomeautoarchive/content/aop.jsm:63:6
aspect@chrome://awsomeautoarchive/content/aop.jsm:63:20
archiveMessages@chrome://messenger/content/mailWindowOverlay.js:1690:5
searchListener/this.processHeaders@chrome://awsomeautoarchive/content/autoArchiveService.jsm:681:11
searchListener/this.onSearchDone@chrome://awsomeautoarchive/content/autoArchiveService.jsm:532:9

can't be sure if it's killing the archive process, but it comes up with each run of the service.
Looks somewhat related to other "old is null", but failing at a different point.
The older version didn't work at all, so...