Hartman’s Law of Prescriptivist Retaliation: “any article or statement about correct grammar, punctuation, or spelling is bound to contain at least one eror”.
I wondered if the misspelling of “error” was in the original; it isn’t. (I really should have
realized that it wasn’t an exact copy of the original from its not starting with a capital.
Also, the statement isn’t itself about correct g/p/s, so that wouldn’t be a valid joke.)