Zapier Cli未处理错误：文件哈希应用静默失败排查

我开发了一款Zapier应用，核心功能是接收文件作为输入并返回其SHA256哈希值。正常输入文件时应用运行没问题，但如果输入非文件内容（比如字符串），应用会出现静默失败：只有日志里能看到模糊的堆栈跟踪，Zapier界面没有任何错误提示，还会返回错误的哈希值。

一开始我以为这个错误没法通过代码处理，而且日志里的堆栈信息乱码还模糊：

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我的代码是基于Zapier的文件示例应用修改的，只替换了creates/uploadFile.js，原代码如下：

const request = require('request'); 
const crypto = require('crypto'); 

function hashStream(stream) { 
  const hash = crypto.createHash('sha256').setEncoding('hex'); 
  return new Promise((resolve, reject) => { 
    stream.pipe(hash) 
      .on('finish', () => resolve(hash.read())) 
      .on('error', reject) 
  }) 
} 

function hashFile(z, bundle) { 
  const fileStream = request(bundle.inputData.file); 
  return hashStream(fileStream).then((hash) => ({hash})); 
}; 

module.exports = { 
  key: 'hashFile', 
  noun: 'File', 
  display: { 
    label: 'Hash File', 
    description: 'Performs a sha256 on file.' 
  }, 
  operation: { 
    inputFields: [ 
      {key: 'file', required: true, type: 'file', label: 'File'}, 
    ], 
    perform: hashFile, 
    sample: { filename: 'example.pdf' }, 
    outputFields: [ 
      {key: 'hash', type: 'string', label: 'Hash'} 
    ], 
  } 
}; 

问题解决更新 #

后来我找到了问题根源：我之前默认request函数在请求失败时会直接抛出错误，但实际上它没有——反而会把错误页面的内容当成文件流来计算哈希，导致返回错误的哈希值。修改hashFile函数后解决了这个问题：

function hashFile(z, bundle) { 
  return new Promise((resolve, reject) => { 
    request(bundle.inputData.file) 
      .on('response', function ({statusCode}) { 
        if (200 === statusCode) { 
          hashStream(this).then((hash) => resolve({hash})); 
        } else { 
          reject(new Error(`Invalid status code ${statusCode}`)); 
        } 
      }) 
      .on('error', (err) => reject(err)) 
  }) 
} 

不过还有个遗留问题：我没法捕获日志里的“未处理错误”。我试过用下面的代码，但完全没效果，猜测是Zapier引擎限制了这类全局事件监听：

process.on('unhandledRejection', (reason, p) => { 
  console.log('Unhandled Rejection at:', p, 'reason:', reason); 
  process.exit(1); 
}); 

内容的提问来源于stack exchange，提问作者max-lt