chore: fixed incorrect error

app/models/team.rb

@@ -78,7 +78,7 @@ def full?
 
   # Add member to the team, changed to hash by E1776
   def add_member(user, _assignment_id = nil)
-    raise "The user #{user.name} is already a member of the team #{name}" if user?(user)
+    raise "The user #{user.username} is already a member of the team #{name}" if user?(user)
 
     can_add_member = false
     unless full?
@@ -87,7 +87,7 @@ def add_member(user, _assignment_id = nil)
       parent = TeamNode.find_by(node_object_id: id)
       TeamUserNode.create(parent_id: parent.id, node_object_id: t_user.id)
       add_participant(parent_id, user)
-      ExpertizaLogger.info LoggerMessage.new('Model:Team', user.name, "Added member to the team #{id}")
+      ExpertizaLogger.info LoggerMessage.new('Model:Team', user.username, "Added member to the team #{id}")
     end
     can_add_member
   end