Help me to make global music in project PLZ

Question

If you can...Plz help me to make global music in all scenes

Now I have

extends Control

# Load the music player node
onready var _player = $AudioStreamPlayer


# Calling this function will load the given track, and play it
func play(track_url : String):
    var track = load(track_url)
    _player.stream = track
    _player.play()

# Calling this function will stop the music
func stop():
    _player.stop()

But code shows me

Invalid set index 'stream' (on base: 'null instance') with value of type 'AudioStreamOGGVorbis'

On other scene I summon my PLAY function

Music.play("res://SFX/zvuki-signal-trevogi.ogg")

Comments

From the looks of it, the variable _player in the _play() function is null. In that "other scene", it may have a $AudioStreamPlayer, while the original scene does not.