Opening Calypso on scope ‘Full environment’ signals MessageNotUnderstood

[Rinzwind]

In Pharo 13 build 478, a MessageNotUnderstood (“Instance of RBBrowserEnvironment did not understand #definedClasses”) is signaled when selecting ‘Open on Calypso’ in the context menu on ‘Full environment’ in the Scope(s) Editor.

[Rinzwind]

I checked earlier builds: a MessageNotUnderstood is signaled in build 228, but not in build 227. I’m guessing this issue is due to the changes in pull request #16852 by @carolahp.