added music and now its showing an error

hi so im new to gamemaker and i'm trying to add music to my game and it worked but now when i try to open the game, it shows me an error and im super confused.


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ERROR in action number 1
of Other Event: Room Start for object obj_game_manager:
Variable <unknown_object>.snd_music_menu(100046, -2147483648) not set before reading it.
at...

added music and now its showing an error