在 node.js 运行中，当遇到 UnhandledPromiseRejectionWarning 错误或警告时，该如何解决呢？错误提示有时候是这样的：

(node:6603) UnhandledPromiseRejectionWarning: Error: Protocol error (Runtime.callFunctionOn): Object reference chain is too long

有时候是这样的：

(node:6603) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch().

问题在于未捕捉的异常，解决办法就是加一个处理句柄，专门处理这个抛出错误（promise rejection）：

process.on('unhandledRejection', (reason, p) => {
  console.log('Promise: ', p, 'Reason: ', reason)
  // do something
})