What is the test for error in failing to instruct a student on the mistake-of-fact defense?

"'Error in failing to instruct on the mistake-of-fact defense is subject to the harmless error test set forth in People v. Watson (1956) 46 Cal.2d 818, 836 . . . . [Citation.]' [Citation.] Under this standard, a conviction 'may be reversed in consequence of this form of error only if, "after an examination of the entire cause, including the evidence" [citation], it appears "reasonably probable" the defendant would have obtained a more favorable outcome had the error not occurred [citation].'" (Hanna, supra, 218 Cal.App.4th at pp. 462-463.)