What is the basis for a motion for a mistrial?

Regardless of the basis for a mistrial motion, the rules governing our review are the same." 'A mistrial should be granted if the court is apprised of prejudice that it judges incurable by admonition or instruction. [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.]' [Citation.] A motion for a mistrial should be granted when ' " 'a [defendant's] chances of receiving a fair trial have been irreparably damaged.(People v. Collins (2010) 49 Cal.4th 175, 198.)