a.js

async (next) => {
  const x = await f1();
  if (x) {
    return next();
  }
  f2(() => {
    f3();
    next();
  });
  // fails eslint  consistent-return
}


async (next) => {
  const x = await f1();
  if (x) {
    return next();
  }
  await new Promise((resolve) => {
    f2(() => {
      f3();
      resolve();
    });
  });
  return next(); // passes eslint
}