Fix crashes in rooms 9 and 13 (#415)

addons/escoria-core/game/core-scripts/esc/commands/inc_global.gd

@@ -27,7 +27,7 @@ func validate(arguments: Array):
 			]
 		)
 		return false
-	if not escoria.globals_manager.get(arguments[0]) is int:
+	if not escoria.globals_manager.get_global(arguments[0]) is int:
 		escoria.logger.report_errors(
 			"inc_global: invalid global",
 			[

addons/escoria-core/game/scenes/camera_player/esc_camera.gd

@@ -195,7 +195,7 @@ func target_reached():
 func _process(_delta):
 	zoom_transform = self.get_canvas_transform()
 
-	if follow_target and not tween.is_active() and follow_target.has_moved():
+	if is_instance_valid(follow_target) and not tween.is_active() and follow_target.has_moved():
 		self.global_position = follow_target.global_position
 
 func _ready():