Calling appendPart(InstrumentName) on the active score causes MuseScore to crash.

I'm trying to develop a plug-in that will produce music in parallel with the current selection, so I've been trying to append a new part to the score. This causes the above problem which I've successfully replicated in musescore 0.9.6 with the plug-in code below.

var mscorePlugin =
{
majorVersion: 1,
minorVersion: 1,
menu: 'Plugins.mytest',
init: init,
run: run,
onClose: close
};

function init() {};

function run() {
curScore.appendPart("Piano");
};

function close() {};

mscorePlugin;