Bad input to the ``broadcast_to`` function triggers an internal-check error

[JoelPasvolsky]

The broadcast_to below triggers an error

>>> broadcast_to(model.constant([[2, 3], [4, 5]]), model.constant(5))
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

on the code checking for whether the symbol needs to be reshaped or not: if x.shape() == shape or (isinstance(shape, int) and x.shape() == (shape,))

[arcondello]

I think this is just a case where duck typing means we cannot capture all possible cases. It expects a valid shape as input, you're handing it something that's invalid. The error that happens when you try to test equality will vary by the object. FWIW, a type checker should warn before you get here.