enthought/traitsui — comment on commit a44361092424d752e1a494fc207f6a6639cad4cd
File:  line 0
By jdmarch:

I wonder whether this should just log a warning for now instead of re-raising, especially since this is only targeted at a point release of ETS.

This could break existing applications which (if only accidentally) relied on this check being weak.

This actually was the case with an application in development which added a trait dynamically, before it was actually displayed but after the View referring to it was initialized. Definitely a bug (now fixed), but also apparently harmless.