You should be able to get a property by drag and droping the component on the canvas and selecting the property you want.
Did you do that this way, or some other way, like for example through “Bound Variables” on the Blackboard, which should also work fine by the way.
The error you post here is nasty and should not appear. Can you please do an export to json from the “File” menu and send it to me? info_at_nodecanvas.com.