Comment 11 for bug 234224

Sounds weird.
I do:
    uplevel #0 namespace import ::msgcat::mc
which defines the 'mc' command. One possible reason for this bug is if
there is an error dialog or something else that uses 'mc' before it
was imported from ::msgcat::mc. Try run the source distro but do:

wish or wish8.5
namespace import ::msgcat::mc
source Coccinella.tcl

to be sure 'mc' is defined before its usage.
In any case I just checked in a few fixes where I switched to
::msgcat::mc in cases before the import. See if this helps. If my
assumption is right you will likely see a dialog:
"Error reading preference file: $prefsFilePath."
which says you don't have read access to the prefs path.