Former President Donald Trump’s witness at his Manhattan criminal trial raised a massive stir after his conduct forced Judge Juan Merchan to clear the courtroom — but that’s not all that happened. Merchan further threatened that he would remove Robert Costello from the witness stand if there were any further breaches of decorum in the courtroom, according to court transcripts obtained by Lawfare’s Anna Bower. Costello, the former legal adviser for Trump’s estranged attorney and fixer Michael Cohen, was called to court at Trump’s insistence — reportedly over the misgivings of some of his legal …