[Dev] Fix `__repr__()` errors in REPL when referencing an instance of a class

[Kreusada]

Description of the changes

I have noticed that when __repr__() is to raise an exception, the [p]repl command fails, and the exception is explicitly raised instead of being sent as a message in the session. However, this only happens when the instance is referenced (object()) and not when the repr() function is used (repr(object())).

Take the following code, for example:

class A(object):
    def __repr__(self) -> str:
        raise Exception

If we were to type A(), Exception would be explicitly raised as a command error. However, typing repr(A()) would behave as you would expect.

I discovered this with my own code in a REPL session:

def __repr__(self) -> str:
    attrs = {n[1:]: getattr(self, n) for n in self.__slots__}
    join = ", ".join(f"{k}={v!r}" for k, v in attrs.items())
    return f"{self.__class__.__name__}({join})"

I had not included the __slots__ definition within the class, hence why an AttributeError was raised when I typed "MyClass()". I was expecting this error to be printed in the session's channel, not to error the command.

Have the changes in this PR been tested?

Yes, working