Allow Anchor poses to be null

Author: alcooper91

hit-test-anchors.html

@@ -217,7 +217,9 @@
             continue;
           }
           const anchorPose = frame.getPose(anchor.anchorSpace, xrRefSpace);
-          anchoredObject.matrix = anchorPose.transform.matrix;
+          if (anchorPose) {
+            anchoredObject.matrix = anchorPose.transform.matrix;
+          }
         }
 
         scene.startFrame();
@@ -233,4 +235,4 @@
       initXR();
     </script>
   </body>
-</html>
+</html>