Tomboy error: "DoHighlight: null pointer error for ..."

Binary package hint: tomboy

When I run Tomboy from the command line (tomboy --debug) I often see one or more errors of the following kind printed when I edit a note, e.g.:

[DEBUG 13:25:45.734] DoHighlight: null pointer error for 'pr'.
[DEBUG 13:25:45.734] DoHighlight: null pointer error for 'proper'.
[DEBUG 13:25:46.709] DoHighlight: null pointer error for 'pr'.
[DEBUG 13:25:46.709] DoHighlight: null pointer error for 'proper'.
[DEBUG 13:25:57.811] DoHighlight: null pointer error for 'andr'.
[DEBUG 13:25:58.649] DoHighlight: null pointer error for 'andr'.
[DEBUG 13:26:01.019] DoHighlight: null pointer error for 'tr'.
[DEBUG 13:26:01.849] DoHighlight: null pointer error for 'tr'.
[DEBUG 13:26:03.285] DoHighlight: null pointer error for 'tr'.
[DEBUG 13:26:03.991] DoHighlight: null pointer error for 'tr'.
[DEBUG 13:26:04.545] DoHighlight: null pointer error for 'tr'.
[DEBUG 13:26:04.896] DoHighlight: null pointer error for 'tr'.
[DEBUG 13:26:05.592] DoHighlight: null pointer error for 'tr'.
[DEBUG 13:26:06.215] DoHighlight: null pointer error for 'tr'.

These errors appear to occur only for some notes, and for the affected notes, the errors only occur sometimes, depending on where in the note I edit.

There is no loss of functionality as far as I can see.

If I create a new note, and edit it, the errors do not occur.

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: tomboy 1.4.2-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.35-28.49-generic 2.6.35.11
Uname: Linux 2.6.35-28-generic x86_64
Architecture: amd64
Date: Mon Mar 21 13:26:57 2011
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100429)
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: tomboy