In Virginia, non-constitutional error "is harmless 'when it plainly appears from the record and the evidence given at the trial that the parties have had a fair trial on the merits and substantial justice has been reached.'" Lavinder v. Commonwealth, 12 Va. App. 1003, 1005, 407 S.E.2d 910, 911 (1991) (en banc) (quoting Code 8.01-678). "An error does not affect a verdict if a reviewing court can conclude, without usurping the jury's fact finding function, that, had the error not occurred, the verdict would have been the same." Id. "The effect of an error on a verdict varies widely 'depending upon the circumstances of the case.' Each . . . must . . . be analyzed individually to determine if an error has affected the verdict." Id. at 1009, 407 S.E.2d at 913.