BUG: Error reading xmp:subject from some images

[IonoclastBrigham]

Got the following error whenever it tries to read the subject field from certain images (see attached for example):

map: contract violation
  expected: list?
  given: #f
  context...:
   /Applications/Racket v7.0/collects/racket/private/map.rkt:180:2: check-args
   /Applications/Racket v7.0/collects/racket/private/map.rkt:257:2: gen-map
   /Users/prime/Code/ivy/meta-editor.rkt:236:17
   /Applications/Racket v7.0/share/pkgs/gui-lib/mred/private/wx/common/queue.rkt:428:6
   /Applications/Racket v7.0/share/pkgs/gui-lib/mred/private/wx/common/queue.rkt:479:32

It appears to be the xmp:subject field specifically, for the given image, though it might be a red herring. The image has not otherwise been loaded or edited by Ivy.