bzr: ERROR: exceptions.TypeError: list indices must be integers, not NoneType

I merged some changes from another branch, one of which involved deleting some empty folders. This resulted in a conflict, as there were some backup files existing in the branch I was merging into. I went ahead and deleted the files, then tried to delete the folders using bzr explorer thinking it might resolve the conflict for me. When I tried, bzr explorer crashed. It however did delete the folder in question.

bzr: ERROR: exceptions.TypeError: list indices must be integers, not NoneType

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/uifactory.py", line 32, in decorate
    r = f(*args, **kargs)
  File "/home/dmuir/.bazaar/plugins/explorer/lib/wt_browser.py", line 665, in remove
    treewidget.TreeWidget.remove(self)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/uifactory.py", line 32, in decorate
    r = f(*args, **kargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/treewidget.py", line 2070, in remove
    self.refresh()
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/treewidget.py", line 1565, in refresh
    load_dirs=state[1])
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/treewidget.py", line 539, in set_tree
    initial_checked_paths, load_dirs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/treewidget.py", line 657, in process_inventory
    ignore_no_file_error=True):
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/treewidget.py", line 1129, in refs2indexes
    indexes.append(self.ref2index(ref))
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/treewidget.py", line 1123, in ref2index
    return self._index_from_id(dict[key].id, self.NAME)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr/lib/treewidget.py", line 738, in _index_from_id
    item_data = self.inventory_data[item_id]
TypeError: list indices must be integers, not NoneType

bzr 2.2.3 on python 2.6.5 (linux2)
arguments: ['/usr/bin/bzr', 'explorer']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'en_AU.UTF-8'
plugins:
  bash_completion /usr/lib/python2.6/dist-packages/bzrlib/plugins/bash_completion [2.2.3]
  bzrtools /usr/lib/python2.6/dist-packages/bzrlib/plugins/bzrtools [2.2.0]
  dbus /usr/lib/python2.6/dist-packages/bzrlib/plugins/dbus [0.1.0dev]
  explorer /home/dmuir/.bazaar/plugins/explorer [1.1.3dev]
  extmerge /home/dmuir/.bazaar/plugins/extmerge [unknown]
  git /usr/lib/python2.6/dist-packages/bzrlib/plugins/git [0.5.2]
  gtk /usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk [0.99.0]
  launchpad /usr/lib/python2.6/dist-packages/bzrlib/plugins/launchpad [2.2.3]
  netrc_credential_store /usr/lib/python2.6/dist-packages/bzrlib/plugins/netrc_credential_store [2.2.3]
  news_merge /usr/lib/python2.6/dist-packages/bzrlib/plugins/news_merge [2.2.3]
  qbzr /usr/lib/python2.6/dist-packages/bzrlib/plugins/qbzr [0.19.3]
  rewrite /home/dmuir/.bazaar/plugins/rewrite [0.6.1]
  svn /usr/lib/python2.6/dist-packages/bzrlib/plugins/svn [1.0.4]
  upload /usr/lib/python2.6/dist-packages/bzrlib/plugins/upload [1.0.0]