How to CustomShader (shader compile, [ex syntax error..]) error catch?

I’ve tried setting a try catch in the code that adds the Model but I’m unable to catch the error.
How can I catch CustomShader errors?

try {
    model = await Cesium.Model.fromGltfAsync({
        // ...
    let primitive = viewer.scene.primitives.add(model);
} catch (err) {
    console.log('shader error', err);

I really hope for your reply.