Code error in ValidationError.update_error_dict

[zvikico]

There's a minor bug in ValidationError.update_error_dict. The code receives an error_dict which might be None (and perhaps it should have a default None value).
The code has two options, one when a message_dict exists and one that it doesn't.
If the message_dict exists, the code checks for a null error_dict and returns the message_dict instead.
If the message_dict does not exist, the code assumes the error_dict input is a dict without checking for None.

Here's a suggested alternative for the code:

    def update_error_dict(self, error_dict = None):
        if hasattr(self, 'message_dict'):
            if error_dict:
                for k, v in self.message_dict.items():
                    error_dict.setdefault(k, []).extend(v)
            else:
                error_dict = self.message_dict
        else:
            if error_dict:
                error_dict[NON_FIELD_ERRORS] = self.messages
            else:
                error_dict = { NON_FIELD_ERRORS: self.messages, }
        return error_dict

[Aymeric Augustin]

Change UI/UX from NULL to False.

[Aymeric Augustin]

Change Easy pickings from NULL to False.

[Baptiste Mispelon]

Validation.update_error_dict is only used in Model.full_clean, where it always passes a dictionary (never None).

For this reason, I'm marking this as invalid.

Feel free to reopen this bug if you can provide a concrete example of how this affects you.