What is the test for a motion for a mistrial under the deferential abuse of discretion standard?

We review a trial court's ruling on a motion for a mistrial under the deferential abuse of discretion standard. (People v. Cox (2003) 30 Cal.4th 916, 953, overruled on other grounds in People v. Doolin (2009) 45 Cal.4th 390, 421, fn. 22.) "When a witness's volunteered statement is not attributable to either party, a mistrial is called for only if the misconduct is so inherently prejudicial as to threaten defendant's right to a fair trial despite admonitions from the court. [Citation.] ' " 'Whether a particular incident is incurably prejudicial is by its nature a speculative matter, and the trial court is vested with considerable discretion in ruling on mistrial motions. . . .' [Citation.] A motion for a mistrial should be granted when ' " ' a [defendant's] chances of receiving a fair trial have been irreparably damaged.' " ' " ' [Citation.]" (People v. Molano (2019) 7 Cal.5th 620, 675-676.)