World center needs to be reset as well.

src/babylon.scene.ts

@@ -4662,8 +4662,10 @@
 
                 var camera: TargetCamera;
                 var radius = worldSize.length() * 1.5;
+                // empty scene scenario!
                 if (!isFinite(radius)) {
                     radius = 1;
+                    worldCenter.copyFromFloats(0, 0, 0);
                 }
                 if (createArcRotateCamera) {
                     var arcRotateCamera = new ArcRotateCamera("default camera", -(Math.PI / 2), Math.PI / 2, radius, worldCenter, this);