Fix async method tracing

[half0wl]

With @Service({ trace: true }), async methods were not getting traced correctly.

wrapWithTracing is passing a sync callback () => original.apply(this, args) to the trace function for all methods, including async ones. Some tracer fns (e.g. DD APM's tracer.trace) closes the span immediately when the callback returns synchronously even if the retval is a Promise.

This fixes it by detecting AsyncFunction methods and pass async () => original.apply(this, args) so tracing libraries that inspect the callback's constructor (DD APM, OpenTelemetry) keep the span open until the promise settles.

[railway-app]

🚅 Deployed to the container-pr-1 environment in 😸 ray.cat

Service	Status	Web	Updated (UTC)
container.lib.ray.cat	🕗 Deploying (View Logs)	Web	Mar 17, 2026 at 5:10 pm