#822 "ValidationError" and "HttpError" are not unpicklable

[AlTosterino]

I'm using loguru for logging and had hard time debugging TypeError: ValidationError.__init__() missing 1 required positional argument: 'errors' while calling logger.exception in Ninja api.on_exception. This is addressing the issue.

Fixes #822

[OtherBarry]

Minor nitpick, but it should be picklable and unpicklable, with an L, according to the python documentation.

[AlTosterino]

@OtherBarry Oh my I didn't even notice... Thanks!

I also deleted __reduce__ method as super().__init__(...) did the trick 👌

[vitalik]

Thank you