Update viewer.js

viewer.js

@@ -133,7 +133,7 @@ export async function initializeViewer(config, instanceId) {
   const assets = {
     sogs: new pc.Asset('gsplat', 'gsplat', { url: sogsUrl }),
     orbit: new pc.Asset('script', 'script', { url: "https://mikafil-viewer-gs.static.hf.space/orbit-camera.js" }),
-    glb: new pc.Asset('glb', 'container', { url: glbUrl }),
+    glb: glbUrl ? new pc.Asset('glb', 'container', { url: glbUrl }) : null,
   };
   for (const key in assets) app.assets.add(assets[key]);