What is the test for determining whether an aider and abettor is liable for any other crime that was a "natural and probable consequence" of the crime?

As explained in People v. McCoy (2001) 25 Cal.4th 1111 (McCoy), "an aider and abettor's liability for criminal conduct is of two kinds. First, an aider and abettor with the necessary mental state is guilty of the intended crime. Second, under the natural and probable consequences doctrine, an aider and abettor is guilty not only of the intended crime, but also 'for any other offense that was a "natural and probable consequence" of the crime aided and abetted.' (People v. Prettyman [(1996)] 14 Cal.4th [248,] 260.)" (25 Cal.4th at p. 1117.) However, in this case, as in McCoy, "the trial court did not instruct the jury on the natural and probable consequences doctrine. It instructed only on an aider and abettor's guilt of the intended crimes. Accordingly, only an aider and abettor's guilt of the intended crime is relevant here." (Ibid.)