That won't work in IDLE because IDLE replaces the standard sys.stdout file object with a special proxy object to capture stdout across its processes and the proxy object does not currently support all of the attributes of a io.TextTIOWrapper object, like errors.

>>> sys.stdout
<idlelib.rpc.RPCProxy object at 0x1282b30>

If that is the only problem, perhaps this issue should be reassigned to IDLE to support errors and any other relevant new attributes.