What is the test for a jury to determine that there was an error in instructing the jury to produce an unlawful intent to kill?

People v. Swain (1996) 12 Cal.4th 593, 601, 49 Cal.Rptr.2d 390, 909 P.2d 994 [proof of an unlawful intent to kill is the functional equivalent of express malice].) He argues further the instructional error was compounded by weak evidence of deliberation.

When we review challenges to a jury instruction as being incorrect or incomplete, we evaluate the instructions as a whole, not in isolation. [Citation.] For ambiguous instructions, the test is whether there is a reasonable likelihood that the jury misunderstood and misapplied the instruction. (People v. Rundle (2008) 43 Cal.4th 76, 149, 74 Cal.Rptr.3d 454, 180 P.3d 224.)