TypeError: Error #1009: but the debugger says that the object is valid

I ran into a problem where I was getting a TypeError: Error #1009: Cannot access a property or method of a null object reference while the debugger was reporting that the object was not null. Traces report that the object is null, but the variables list in debug view or rolling over the variable reported that it was po开发者_如何学Pythonpulated with an object.

The answer ended up being that I had a class and a subclass, each with a private var of the same name. The variable was populated in the subclass but not the superclass. The debugger did not differentiate between the two, and was reporting an incorrect value. This appears to be a debugger bug.