What is the test for instructing a jury on the lesser included offense of "imperfect self-defense" in a murder case?

"Instructions on lesser included offenses ' "are required whenever evidence that the defendant is guilty only of the lesser offense is 'substantial enough to merit consideration' by the jury. [Citations.] 'Substantial evidence' in this context is ' "evidence from which a jury composed of reasonable [persons] could . . . conclude[ ]" ' that the lesser offense, but not the greater, was committed." ' " (People v. Prince (2007) 40 Cal.4th 1179, 1265.) " 'The erroneous failure to instruct on a lesser included offense generally is subject to harmless error review under the standard of People v. Watson (1956) 46 Cal.2d 818, at pages 836-837. Reversal is required only if it is reasonably probable the jury would have returned a different verdict absent the error or errors complained of.' " (Prince, at p. 1267.)

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"Imperfect self-defense, which reduces murder to voluntary manslaughter, arises when a defendant acts in the actual but unreasonable belief that he is in imminent danger of death or great bodily injury. [Citations.] Heat of passion, which likewise reduces murder to voluntary manslaughter, arises when the defendant is provoked by acts that would 'render an ordinary person of average disposition "liable to act rashly or without due deliberation and reflection, and from this passion rather than from judgment" ' [citation] and kills while under the actual influence of such a passion." (People v. Duff (2014) 58 Cal.4th 527, 561-562.)