Using guard clauses. Way more readable and easy to work with.

  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;
  }