getEnv() for platform "browser" does not work with service workers

[svrnm]

What version of OpenTelemetry are you using?

0.19

What did you do?

I try to use opentelemetry-web & opentelemetry-tracing within a Service Worker

What did you expect to see?

A working tracer.

What did you see instead?

An error that window is not defined in getEnv, since Service Worker do have a different global object, i.e. self

Additional context

Looking into getEnv() for the browser, it's clear that this issue comes from a dependency on window:

export function getEnv(): Required<ENVIRONMENT> {
  const _window = window as typeof window & RAW_ENVIRONMENT;
  const globalEnv = parseEnvironment(_window);
  return Object.assign({}, DEFAULT_ENVIRONMENT, globalEnv);
}

I could work around this issue by adding the following code to my service worker:

export type {};
interface MyServiceWorkerGlobalScope extends ServiceWorkerGlobalScope {
  window: unknown;
}
declare const self: MyServiceWorkerGlobalScope;
if (self.constructor.name !== 'Window') {
  self.window = self;
}

I am not sure if something like the following would do the trick:

const _window = window ? (window as typeof window & RAW_ENVIRONMENT) : (self as ???);

or, since all modern browsers have window.self as well (source) the following:

// const _window = window as typeof window & RAW_ENVIRONMENT;
const _window = self as typeof window & RAW_ENVIRONMENT;

[dyladan]

const _window = window ? (window as typeof window & RAW_ENVIRONMENT) : (self as ???); is similar to what we've done in the API and other places https://github.com/open-telemetry/opentelemetry-js-api/blob/41109c83a9784d689f319f2c5d953b3874c694a3/src/platform/browser/globalThis.ts#L19

[svrnm]

const _window = window ? (window as typeof window & RAW_ENVIRONMENT) : (self as ???);

Looks like there is still a lot of TypeScript I have to learn 🤣

I'll try to come up with an PR for that, thanks for calling out the existing solution in the api