Why Unity hang when my if statement fail

Hello, I have a problem, I am making a level generator that generates a branch of rooms. In one of my tests I discovered that there was a chance that several rooms could overlap with other rooms. So after a little bit of google research I did this :

 void GenerateBranch()
     {
         int i = 0;
 
         while (i < branchLength)
         {
             // We make sure that the room is not overlapping another one.
             if (!groupPos.Contains(new Vector2(currentPosX, currentPosY)))
             {
                 groupPos.Add(new Vector2(currentPosX, currentPosY));

                 // the generation process is normally here but I don't show you it because it is too long
                 i++;
             }
             else
             {
                 Debug.Log("The level generation was creating room over the other one, we stopped this action");
                 i--;
             }
         }
     }

the program is working fine but when the program detects that a room is going to overlap another one Unity freezes.