@cpennington Did you mean that it would cause problems for other subclasses of RawDescriptor that DID expect self.data to be empty?  If you del foo.data, then I think there would be a problem on export (the same problem that word cloud is having right now). What would be the use case for expecting foo.data to be empty?

Peter can go back to the wordcloud-specific fix, and perhaps that is the best approach. But I am concerned that the same bug will creep up in new xmodules (with no data). Although perhaps we artificially created the no-data situation by too zealously moving things into fields with Scope.settings (vs. Scope.content).