Error when calling plot or fix symbolic because acts is not an attribute

[antngh]

Similar to here

I get an attribute error when calling some methods (namely plot) after I've trained a model if I haven't first run a forward inference pass on the model, this is because acts is set in the forward method.

I propose adding these two functions to KAN:

    @property
    def acts(self) -> list:
        """
        Acts attribute getter, raises an error if it does not exist.

        Returns:
        --------
            acts : list
                activations of each layer
        """
        if not hasattr(self, "_acts"):
            raise RuntimeError(
                "No acts attribute. Please run a forward pass of the model first."
            )
        return self._acts

    @acts.setter
    def acts(self, value: list):
        """
        Set the acts list attribute.

        Args:
        -----
            value:

        Returns:
        --------
            None

        """
        setattr(self, "_acts", value)

So that if it happens, it's clear that the model needs to be called first. Otherwise it's a bit opaque what the issue is.

There might be a larger issue though, I think that the model should be plotable after training, but this would be a quick intermediate fix.

Thanks