Calling undefined getter on self defined class instance yields global variable

[Quijx]

Describe the bug When calling a non existing getter with the same name as a global variable on another global variable that holds an instance of a self defined class, the value of the first global variable is returned, instead of throwing a NoSuchMethodError.

To Reproduce

1. Enter the following lines in order:

   
   >>> a=1
   1
   >>> class Foo {}
   >>> f=Foo()
   >>> f.a
   1

**Expected behavior**
A `NoSuchMethodError` is thrown, just like if you were to define `f='a string'` instead of `f=Foo()` for example.

**Actual Behavior**
The value of the global variable `a` is returned even though an instance of the class `Foo` clearly does not have a getter called `a`.

[welcome[bot]]

Hi! Thanks for opening your first issue here! :smile:

[fzyzcjy]

You are right, feel free to PR!

A good starting point is to look at the generated.dart file to see what is indeed generated