User not in the room: This occurs when the userId doesn't belong to any user in the room.
Invalid User: This occurs when the userId doesn't belong to any user in the workspace.
User is already a Leader: This occurs when user is already a leader in that room.
No Permission: This occurs when the authenticated user does not have the set-leader permission.
{"msg":"result","id":"2","error": {"isClientSafe":true,"error":"error-user-not-in-room","reason":"User is not in this room","details": {"method":"addRoomLeader" },"message":"User is not in this room [error-user-not-in-room]","errorType":"Meteor.Error" }}
{"msg":"result","id":"2","error": {"isClientSafe":true,"error":"error-invalid-user","reason":"Invalid user","details": {"method":"addRoomLeader" },"message":"Invalid user [error-invalid-user]","errorType":"Meteor.Error" }}
{"msg":"result","id":"2","error": {"isClientSafe":true,"error":"error-user-already-leader","reason":"User is already a leader","details": {"method":"addRoomLeader" },"message":"User is already a leader [error-user-already-leader]","errorType":"Meteor.Error" }}