QQmlListProperty error on non-registered type is confusing

During some recent development, I made an error in exposing a class hierarchy to Qml. I essentially defined:

class BaseFoo { }
class MyFoo : public BaseFoo {}

class Bar

In my startup code I did qmlRegisterType on Bar and MyFoo but forgot to do it on BaseFoo. The problem is, the reported error message upon parsing a QML file and trying to define 'foos' was:

Test.qml:4 Invalid property assignment: \"foos\" is a read-only property\n

While it's reasonable that the code failed, the error message is highly confusing.