Added a second item screen to Window_Message, but game freezes when I try to open it

Okay, so, I decided to make a new item window and add it to Window_Message. The thing is, whenever I try to open the thing, the window doesn't open, and the game just freezes.

The relevant code is here:

class Window_Message < Window_Base alias worlds_create_all_windows create_all_windows def create_all_windows worlds_create_all_windows @item_window2 = Window_SelectItem.new(self) end def process_input if $game_message.choice? input_choice elsif $game_message.num_input? input_number elsif $game_message.item_choice? input_item if $game_variables[$game_message.item_choice_variable_id] == 0 input_item2 end else input_pause unless @pause_skip end end def input_item2 puts "Hello!" # this command runs @item_window2.start puts "Get ready!" # this command also runs Fiber.yield while @item_window2.active puts "Goodbye!" # this command never runs endendclass Window_SelectItem < Window_KeyItem #-------------------------------------------------------------------------- # * Start Input Processing #-------------------------------------------------------------------------- def start self.category = :item update_placement refresh select(0) open activate endendAny ideas?