Does the court have a sua sponte duty to instruct the jury that knowledge of nature of a silencer was not a fact or constructive possession?

In this case, however, respondent urges, and we agree, that there was no sua sponte duty to so instruct because the jury was instructed that possession included actual or constructive possession and, thus, necessarily found appellant knew of its "presence." Thus, the jury necessarily determined that appellant was aware of the presence of the silencer in finding he "possessed" it. More importantly, however, even if the court erred here, the error was clearly harmless as appellant admitted to an officer that he had knowledge of the presence of a silencer in his apartment when he admitted knowledge of a permit for the silencer; he simply denied any of it belonged to him. Given the uncontradicted testimony that appellant stated he had knowledge of the permit for a silencer, the error of instructing regarding knowledge of presence is harmless beyond a reasonable doubt. (Chapman v. California, supra, 386 U.S. 18.)

2. Knowledge of nature