return emptyList passes instead of null

h3d/pass/Default.hx

@@ -102,7 +102,7 @@ class Default extends Base {
 
 	@:access(h3d.scene)
 	override function draw( passes : h3d.pass.PassList ) {
-		if( passes == null )
+		if( passes.isEmpty() )
 			return;
 		for( g in ctx.sharedGlobals )
 			globals.fastSet(g.gid, g.value);

h3d/scene/Renderer.hx

@@ -23,6 +23,7 @@ class Renderer extends hxd.impl.AnyProps {
 	var defaultPass : h3d.pass.Base;
 	var passObjects : SMap<PassObjects>;
 	var allPasses : Array<h3d.pass.Base>;
+	var emptyPasses = new h3d.pass.PassList();
 	var ctx : RenderContext;
 	var hasSetTarget = false;
 
@@ -130,14 +131,14 @@ class Renderer extends hxd.impl.AnyProps {
 
 	function get( name : String ) {
 		var p = passObjects.get(name);
-		if( p == null ) return null;
+		if( p == null ) return emptyPasses;
 		p.rendered = true;
 		return p.passes;
 	}
 
 	function getSort( name : String, front2Back = false ) {
 		var p = passObjects.get(name);
-		if( p == null ) return null;
+		if( p == null ) return emptyPasses;
 		depthSort(p.passes, front2Back);
 		p.rendered = true;
 		return p.passes;