Donald Trump is on a losing streak in his legal cases, a law professor told the former president’s niece, Mary Trump, in an interview published Tuesday. “Any day is a good day if Donald Trump is losing and that was today,” said Jen Taub during the conversation. “And so sorry. I know I’ve heard he may be a family member of yours, and I don’t mean any offense, Mary.” Mary Trump, who has herself been a vocal critic of her genetic relative, asked Taub about how “it’s a terrible day for Donald legally in three separate cases.” Taub replied beginning with the case involving defamation and sexual ass…