exception thrown when yargs.parsed.newAliases is undefined

[oscarocornejo]

Found something of an issue when using yargs.showHelp()
L761

it seems that when self._parseArgs(processArgs) is called, it is not saving the results to self.parsed

if you put a breakpoint on this line: L1012, you will see that the self.parsed property contains the appropriate items.

however, after this function is done, on L762,
self.parsed is set back to false instead of an object. this leads to their being a parse error:

TypeError: Cannot convert undefined or null to object
.concat(Object.keys(yargs.parsed.newAliases) || [])

under function: usage.showHelp( L240

Thanks! 👍

[mleguen]

I just ran into this when trying to answer @varl 's question in #1137.

The problem is not parsed being overwritten, but the returned value of require("yargs") having its properties (not its functions) frozen at their inital value (false for parsed).

So:

const yargs = require("yargs")
yargs.parse()
console.log(yargs.parsed)

returns false, whereas:

const yargs = require("yargs")
y = yargs.parse()
console.log(y)

returns the expected parsed object.

This is due to the way singletonify() in index.js is written.

I'll try to correct this behavior.

[mleguen]

I am unable to reproduce the issue, so I was probably wrong when thinking it was related to require("yargs") properties being frozen.

@oscarocornejo I know it's been a while, but could you please give us some sample code reproducing the issue?

[bcoe]

@oscarocornejo, with @mleguen's work investigating this issue, I ultimately opted to deprecated accessing yargs.parsed, which has issues when used in conjunction with commands (which require tracking state across multiple invocations of the parser).

Do you think you can instead use yargs.parse() or yargs.argv's return value?

[oscarocornejo]

That should be fine, thanks guys 👍

[mleguen]

Closing, as self.parsed is officially no longer supported since 14.0.0.

[gajus]

I am seemingly getting the same error in 14.0.0.

I don't have much to share other than this is how I intialize the code:

yargs
  .env('ADM')
  .commandDir('commands')
  .help()
  .wrap(80)
  .parse();

This is the error that I get:

(node:92950) UnhandledPromiseRejectionWarning: TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at Object.help (/Users/gajus/Documents/dev/applaudience/data-manager/node_modules/yargs/lib/usage.js:240:22)
    at Object.self.showHelp (/Users/gajus/Documents/dev/applaudience/data-manager/node_modules/yargs/lib/usage.js:432:15)
    at Object.Yargs.self.showHelp (/Users/gajus/Documents/dev/applaudience/data-manager/node_modules/yargs/yargs.js:790:11)
    at Object.fail (/Users/gajus/Documents/dev/applaudience/data-manager/node_modules/yargs/lib/usage.js:50:17)
    at /Users/gajus/Documents/dev/applaudience/data-manager/node_modules/yargs/lib/command.js:239:36
    at processTicksAndRejections (internal/process/task_queues.js:85:5)

[gajus]

yargs/lib/usage.js

Line 240 in 8792d13

.concat(Object.keys(yargs.parsed.newAliases) || [])

Here yargs.parsed.newAliases is undefined when this happens.

[gajus]

My builder is simply:

export const builder = (yargs: Object): void => {
  yargs
    .options({
      'cinema-data-scraper-sources-path': {
        demand: true,
        description: 'Path to the directory that includes the cinema data scraper sources.',
        type: 'string',
      },
      // [..]
    });
};

[bcoe]

@gajus mind opening a new issue calling out this specific error?

[bcoe]

@gajus actually, I went ahead and reopened this issue with a new title 👍

Can you figure out a reproduction that doesn't involve a command directory?

require('./')
  .env('ADM')
  .command('my-cool-command', 'description', (yargs) => {
  yargs
    .options({
      'cinema-data-scraper-sources-path': {
        demand: true,
        description: 'Path to the directory that includes the cinema data scraper sources.',
        type: 'string',
      },
      // [..]
    });
  }, () => {})
  .help()
  .wrap(80)
  .parse();

👆 the above works correctly for me.

[gajus]

I have tried a bunch of cases and I cannot replicate this without using command directory.

[gajus]

Will give it a try tomorrow again.

[gajus]

I cannot replicate it in a single file, but with commands it is easy:

// ./bin.js
require('yargs')
  .commandDir('commands')
  .parse();

// ./commands/foo.js
module.exports = {
  command: 'foo',
  desc: '',
  builder: () => {},
  handler: async () => {
    throw new Error('test');
  }
};

(node:23038) UnhandledPromiseRejectionWarning: TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at Object.help (/Users/gajus/Documents/dev/temp3/node_modules/yargs/lib/usage.js:240:22)
    at Object.self.showHelp (/Users/gajus/Documents/dev/temp3/node_modules/yargs/lib/usage.js:432:15)
    at Object.Yargs.self.showHelp (/Users/gajus/Documents/dev/temp3/node_modules/yargs/yargs.js:790:11)
    at Object.fail (/Users/gajus/Documents/dev/temp3/node_modules/yargs/lib/usage.js:50:17)
    at /Users/gajus/Documents/dev/temp3/node_modules/yargs/lib/command.js:239:36
(node:23038) 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(). (rejection id: 2)
(node:23038) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

[bcoe]

@gajus you're not using using TypeScript are you? I found a bug that throws similar errors to yours, that happens as a result of:

var __importStar = (this && this.__importStar) || function (mod) {
    if (mod && mod.__esModule) return mod;
    var result = {};
    if (mod != null) for (var k in mod) if (Object.hasOwnProperty.call(mod, k)) result[k] = mod[k];
    result["default"] = mod;
    return result;
};
const yargs = __importStar(require("yargs"));

The __importStar helper in TypeScript executes all the methods on yargs, which in turn seems to put the parser in a strange state. Any thoughts @mleguen? I'm wondering if this could be the root cause of some of the issues we're seeing.

[gajus]

I am not using TypeScript.

[gajus]

What is the problem with this test case?

#1144 (comment)

[bcoe]

@gajus test case should be fine, haven't dug into it too much yet; was just wondering if something similar is being caused by your example, i.e., all the fields being walked on an yargs instance (will need to dig and see).