Add output_transform type check in Metric class

[vfdev-5]

Let's check output_transform input argument type:

class Metric(...):

    def __init__(
        self,
        output_transform: Callable = lambda x: x,
        device: Union[str, torch.device] = torch.device("cpu"),
        skip_unrolling: bool = False,
    ):
        if not callable(output_transform):
            raise TypeError(
                "Argument output_transform should be callable, "
                f"got {type(output_transform)}"
            )
        self._output_transform = output_transform
        ...

TODO:

• Add above code
• Add a test checking that error is raised to https://github.com/pytorch/ignite/blob/master/tests/ignite/metrics/test_metric.py

[github-actions]

Hey 👋, I've just created a thread for this issue on PyTorch-Ignite Discord where you can quickly talk to the community on the topic.

^{🤖 This comment was automatically posted by Discuss on Discord}

[vfdev-5]

Done in #3371