Method writeCallback

lib/internal/http2/core.js:2305–2309

(err)

      cb(err);
    };
    const writeCallback = (err) => {
      waitingForWriteCallback = false;
      writeCallbackErr = err;
      done();
    };
    const endCheckCallback = (err) => {
      waitingForEndCheck = false;
      endCheckCallbackErr = err;