The prosecution is desperately seeking a mistrial. After the cross examination of Gates they know that the best they can get is a hung jury if this trial proceeds to verdict. That would be very bad for Mueller and it would be highly unlikely he would try Manafort again or ever get a conviction. A mistrial is his best option. However the judge’s “error” is not likely the basis for such a ruling.
Declaration of a mistrial over the defendant’s objection offends the Double Jeopardy clause unless it was compelled by a “manifest necessity” (such as a hung jury, death of the judge, that sort of thing).
Mueller is attempting to intimidate the judge.