Fix RayCast2DEditor uninitialized value

node was previously read before being set. Found by Valgrind.

(cherry picked from commit c8a39f6fb3c973c20f14ec6b81d3eb8325e0fbef)

editor/plugins/ray_cast_2d_editor_plugin.h

@@ -41,7 +41,7 @@ class RayCast2DEditor : public Control {
 
 	UndoRedo *undo_redo = nullptr;
 	CanvasItemEditor *canvas_item_editor = nullptr;
-	RayCast2D *node;
+	RayCast2D *node = nullptr;
 
 	bool pressed = false;
 	Point2 original_cast_to;