> This approximates `if` statements being an expression that returns something.

Do you care to elaborate? "if (...) return ...;" looks closer to an expression for me:

  export function extractSearchToken(completionToken: { token: string; isQuoted?: boolean }): string {
    if (completionToken.isQuoted) return completionToken.token.slice(2).replace(/"$/, '');

    if (completionToken.token.startsWith('@')) return completionToken.token.substring(1);

    return completionToken.token;
  }

I’m not strongly opinionated, especially with such a short function, but in general early return makes it so you don’t need to keep the whole function body in your head to understand the logic. Often it saves you having to read the whole function body too.

But you can achieve a similar effect by keeping your functions small, in which case I think both styles are roughly equivalent.