I'm finding that with client side async, the awaited behaviour is often external, heterogeneous and unreliable. When an operation fails, it typically requires a state-machine transition to a failed/retry state or fallback service rather than just bubbling up to a top level handler like a coding error i.e. there is something specific you need to do unlike typical exceptions.

Retrofitting a code base with async I concur that local try / catch has been necessary and has added code complexity and doesn't always feel like an improvement. In contrast, server side async has been much more elegant because the errors with internal async server operations are much more exceptional and don't require so much case specific handling.

You should make your API client layer be able to retry operations (and maybe track the status of a network connection) rather than write catch/then() manually.

It would be nice if it was that easy but if retry behaviour is dependent on the specific operation attempted and the error information in the response then you need some degree of local handling even if its just to prepare information for a generic handler.

Exceptions work best when the error is fatal for the local scope but responses from external services aren't like that. The general problem is that the dividing line between errors and information becomes too blurry - your error might only be information to me. A simple example is where something like axios will (by default) throw on 404 responses but an external api might use 404 to indicate a resource does not exist. If your app logic makes a decision based on this information, you will find yourself using exception handlers for control flow despite not experiencing any actual errors.