What is the test for a motion for a mistrial?

The fundamental idea of a mistrial is that some error has occurred which is too serious to be corrected, and therefore the trial must be terminated, so that proceedings can begin again. [Citation.] (Blumenthal v. Superior Court, supra, 137 Cal.App.4th at p. 678, 40 Cal.Rptr.3d 509 .) We cannot conclude that the court erred in deciding an alternate course of action was appropriate. In addition to the natural benefit the court had of actually observing what happened in the courtroom, it made a reasoned decision based on legally permissible criteria. Therefore, it did not abuse its discretion by denying the motion.