Rachel Riley claims a tweet published by Laura Murray caused her serious harm
Ms Murray, who took role as Labour's complaints chief in 2019, denies the claim
Row began after an egg attack on Jeremy Corbyn during a London mosque trip
Countdown star Ms Riley is suing former Corbyn aide Ms Murray for libel at court
Former Labour staffer's tweet described Ms Riley as 'stupid and dangerous' and accused her of saying the then Labour leader 'deserves to be violently attacked'