The trial court has a duty to instruct the jury, sua sponte, to determine whether a witness was an accomplice in the charged offense, "'"whenever the testimony given upon the trial is sufficient to warrant the conclusion upon the part of the jury that a witness implicating a defendant was an accomplice."'" (People v. Snyder (2003) 112 Cal.App.4th 1200, 1218.) The pattern jury instruction to be given when the accomplice status of a witness is in dispute is CALCRIM No. 334. Accomplice Testimony Must Be Corroborated: Dispute Whether Witness Is Accomplice. Alternatively, if the evidence establishes as a matter of law that a witness was an accomplice, the jury must be so instructed, and the applicable jury instruction is CALCRIM No. 335 Accomplice Testimony: No Dispute Whether Witness Is Accomplice. (People v. Zapien (1993) 4 Cal.4th 929, 982.) In either event, the trial court must also instruct the jury, sua sponte, "'(1) that the testimony of the accomplice witness is to be viewed with distrust , and (2) that the defendant cannot be convicted on the basis of the accomplice's testimony unless it is corroborated . . . .' " (Ibid.) "Nonetheless, 'the failure to instruct on accomplice testimony pursuant to Penal Code, section 1111 is harmless where there is sufficient corroborating evidence in the record. The requisite corroboration may be established entirely by circumstantial evidence. Such evidence "may be slight and entitled to little consideration when standing alone. "' 'Corroborating evidence "must tend to implicate the defendant and therefore must relate to some act or fact which is an element of the crime but it is not necessary that the corroborative evidence be sufficient in itself to establish every element of the offense charged." ' " (People v. Zapien, supra, 4 Cal.4th at p. 982.) The corroborating evidence must also be independent of the accomplice's testimony. (People v. Avila (2006) 38 Cal.4th 491, 562.)