Somewhat unfortunate example on void return type on a fetching function

https://github.com/microsoft/TypeScript-Website/blame/0612591abc2d8292c8ddd084b5fb264f203b7026/packages/documentation/copy/en/declaration-files/Do's and Don'ts.md#L81

Sorry if this is overthinking - i am new to typescript.

You are giving a DO example with an interface called "Fetcher" that defines getObject but returning nothing aka void. I think I got the point of "Do write callback parameters as non-optional", but the context is somewhat unfortunate. Maybe there can be thought of a better example for non-optional callback parameters?
Another way to phrase my thought: Is it a DO to use return type void on a getter-Method?

packages/documentation/copy/en/declaration-files/Do's and Don'ts.md の、81行目付近にあるリンク先の例から始めてください。非オプショナルな callback パラメーターに関する周辺のガイダンスを読み、Fetcher の例がその点と void 戻り値型の問題を明確に区別しているか評価してください。例または文言によって意図したガイダンスがより適切に伝われば完了です。