Stepper: ReferenceError is not shown, instead it get stuck

[hanscau]

Stuck, instead it should show the error:

[martin-henz]

"cannot access 'x' before initialization

That's the correct error message for when the stepper wants to evaluate a name: Genuinely undeclared names are handled by the validator.

So basically, evaluation should get stuck, but the error should be displayed as above.