All service worker code is unable to use asynchronous generator methods due to the Webpack ES6 parser, terser, not supporting it.

I've submitted a PR on terser's GitHub repository to add support for asynchronous generator methods. Once the PR is merged, code can be converted from this format:

  class Foo {
    get bar() {
      return async function* () {
        // ...
      };
    }
  }

to this format:

  class Foo {
    async* bar() {
      // ...
    }
  }

https://github.com/fabiosantoscode/terser/issues/97