Does a murder not occur in the commission of a felony if the felony is merely incidental to the murder?

principle that a murder does not occur in the commission of a felony if the felony is merely incidental to the murder, when the evidence raised no issue as to whether the felony was incidental to the murder]; People v. Guzman (1988) 45 Cal.3d 915, 952 [trial court had no sua sponte duty to clarify the meaning of the phrase "while [defendant] was engaged in . . . the commission of" the felony, where defense did not rely on theory that the murder did not occur while the killer was engaged in the felony and the facts plainly established that it did].)