End of chapter 6. A lot of problems took to much time to solve. It was good to know better Godot internal mechanism.

scripts/title/title_screen.gd

@@ -1,7 +1,7 @@
 extends Control
 
 
-func _on_new_game_button_pressed() -> void:
+func _on_new_game_button_pressed():
 	GameManager.startNewGame()
 	
 	Loader.loadScene(self, "res://scenes/game.tscn")

scripts/title/version_number.gd

@@ -1,6 +1,4 @@
 extends Label
 
-
-# Called when the node enters the scene tree for the first time.
-func _ready() -> void:
+func _ready():
 	text += ProjectSettings.get_setting("application/config/version")