Error msg in Bars validate_series looks wrong

[wdoekes]

        if series.data_type(X) is not Number:
            raise ValueError('Bars only support Number values for the Y axis.')

        if series.data_type(Y) is not Text:
            raise ValueError('Bars only support Text values for the X axis.')

If the Bars are rows of horizontal bars, then the checks are correct, but the error message saying Y should be X, and vice versa.