Cockrell v. State
In Cockrell v. State, 933 S.W.2d 73, 89 (Tex. Crim. App. 1996), the Court held that, in the case of improper prosecutorial argument, even incurable error must be preserved by a request for relief - even when a mistrial is the only relief that can adequately address the error, the defendant must move for a mistrial to complain on appeal.
That the comments came from the judge rather than the prosecutor does not render the error "more" incurable.
Whether the incurable, improper comments come from the prosecuting attorney or the trial judge, the impact is the same: the only way to erase the prejudice flowing from the error is to declare a mistrial.
But by failing to ask for a mistrial, the defendant forfeits the error.
And there are good reasons to require the request for a mistrial.
If a mistrial occurs, then the parties save whatever time they would have expended for the rest of the trial and for the appeal that would have followed.