fails:NameError#receiver returns the object that raised the exception
fails:NameError#receiver returns the Object class when an undefined constant is called without namespace
fails:NameError#receiver returns a class when an undefined constant is called
fails:NameError#receiver returns the Object class when an undefined class variable is called
fails:NameError#receiver returns a class when an undefined class variable is called in a subclass' namespace
fails:NameError#receiver returns the receiver when raised from #instance_variable_get
fails:NameError#receiver returns the receiver when raised from #class_variable_get
fails:NameError#receiver raises an ArgumentError when the receiver is none
