[#153759283] Bug fix: Removing legend and y-axis causes Reload dialog to come up in Mammals doc
[#153759283] Bug fix: Removing legend and y-axis causes Reload dialog to come up in Mammals doc

Removing an attribute can bring a previously unplotted point into the plot, one for which the cell axis has (as yet) no category. We protect against this eventuality.

concord-consortium/codap,concord-consortium/codap,concord-consortium/codap,concord-consortium/codap,concord-consortium/codap