Inviting users with groups field failed when there is an existing user in the list

[techAPJ (Arpit Jalan)]

@gingerman

This code is same before & after the security fix commit

@gingerman

shouldn’t the existing user be added to the group (not topic/PM) before rejecting an invite creation

This used to happen before the security fix as per this line of code.

I wouldn’t revert this code before discussing with @tgxworld and he is away for the week.