go: Could not infer: None
The following results in exception `Could not infer: None` only on Go.
```py
class Foo:
    def bar(self):
        return self.x()
```
This is an intentional error, to force the lack of inference for `self.x`.

All languages other than Go transpile this, and then the compiler/invoker fails.  Go fails to transpile this.  IMO Go should be consistent.