code: function errorHandler(err) {
          // eslint-disable-next-line no-console
          const logErr = logger ? logger.error.bind(logger) : console.log;
          if (cluster.isMaster) {
              logErr(`Error in master with pid: ${process.pid}`);
          } else {
              logErr(`Error in worker: ${cluster.worker.id} pid: ${process.pid}`);
          }
  
          if (err.message) {
              logErr(err.message);
          } else {
              logErr(err);
          }
  
          if (err.stack) {
              logErr(err.stack);
          }
  
          // log saving to disk is async, using hack to give time to flush
          setTimeout(() => {
              process.exit(-1);
          }, 600);
      }
docs: set by initAPI