Use the call screen statement in this case

this particular syntax is very precisely documented in the screens page

game/scripts/rooms/main_room/objects/desk.rpy

@@ -44,14 +44,11 @@ label desk:
 
     #Screens
     play sound "sounds/scroll.ogg"
-    show screen desk_menu
+    call screen desk_menu(_with_none=False) with d1
-    with d1
-
-    $ renpy.dynamic(__choice = ui.interact())
-
-    hide screen desk_menu
     #Do NOT add a transition here!
 
+    $ renpy.dynamic(__choice = _return)
+
 
     #Hermione
     if __choice == "hermione" and states.her.busy:
@@ -241,7 +238,7 @@ screen crystal_ball():
     zorder 8
 
     add "interface/desk/crystal_ball.webp" xpos 268 ypos 0
-    if not ball_hint == None:
+    if ball_hint is not None:
         add "interface/desk/hints/glow.webp" xpos 268+40
         add "interface/desk/hints/"+str(ball_hint)+ ".webp" xpos 268+125 xanchor 0.5