Fault silently allows poking non-existing ports

[rdaly525]

I would expect the following code to raise an error or warning trying to poke a bad port. When you try to peek a bad port, it does error.

tester = Tester(my_circuit)
tester.circuit.NON_EXISTANT_PORT = 5
test.eval()
tester.compile_and_run("verilator")

[leonardt]

Technically this is valid default Python behavior (you can set new attributes on an object), but we can make it an error

[leonardt]

Confirmed, this does work with normal objects (but not when you do object())
E.g.

>>> class A:
...     pass
...

>>> a = A()
>>> a.x = 3