Returns the error as a path to message dictionary. Paths are joined
        with the ``join`` string.

def as_dict(self, join='.'):
        """
        Returns the error as a path to message dictionary. Paths are joined
        with the ``join`` string.
        """
        if self.path:
            path = [str(node) for node in self.path]
        else:
            path = ''
        return { join.join(path): self.message }