TypeError: Cannot read property 'children' of undefined

[binarykitchen]

/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/cheerio/lib/api/traversing.js:10
    return memo.concat(_.filter(elem.children, isTag));
                                    ^

TypeError: Cannot read property 'children' of undefined
    at /home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/cheerio/lib/api/traversing.js:10:37
    at /home/michael-heuberger/Development/videomail.io/node_modules/lodash/lodash.js:779:11
    at /home/michael-heuberger/Development/videomail.io/node_modules/lodash/lodash.js:3923:15
    at baseReduce (/home/michael-heuberger/Development/videomail.io/node_modules/lodash/lodash.js:776:5)
    at Function.reduce (/home/michael-heuberger/Development/videomail.io/node_modules/lodash/lodash.js:7836:14)
    at exports.find (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/cheerio/lib/api/traversing.js:9:17)
    at module.exports (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/cheerio/lib/cheerio.js:86:18)
    at new initialize (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/cheerio/lib/static.js:26:20)
    at initialize (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/cheerio/lib/static.js:23:14)
    at DestroyableTransform._transform (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/index.js:54:34)
    at DestroyableTransform.Transform._read (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/through2/node_modules/readable-stream/lib/_stream_transform.js:172:10)
    at DestroyableTransform.Transform._write (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/through2/node_modules/readable-stream/lib/_stream_transform.js:160:12)
    at doWrite (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:335:12)
    at writeOrBuffer (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:321:5)
    at DestroyableTransform.Writable.write (/home/michael-heuberger/Development/videomail.io/node_modules/robots-generator/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:248:11)
    at write (/home/michael-heuberger/Development/videomail.io/node_modules/gulp/node_modules/vinyl-fs/node_modules/through2/node_modules/readable-stream/lib/_stream_readable.js:623:24)

[jugglinmike]

Thanks for the report! We'll need more information before we're able to help you. Can you share the HTML that is causing Cheerio to throw this error? Please remove any text that is not necessary to reproduce the problem.

[pat-eason]

I can confirm this is happening, ran into it after upgrading to 0.19.0 today. Small demo fails:

const cheerio = require('cheerio');
var $ = cheerio.load('<a href="1">one</a><a href="2">two</a><a href="3">three</a>');
$('a');  // <-- Results in error at line

Any selectors I try fail with the same TypeError: Cannot read property 'children' of undefined response.

[binarykitchen]

@jugglinmike I am afraid this one is difficult to reproduce. It just happened when I upgraded lodash from v3.x to v4.x which is quite a rad change.

Why don't you add an undefined check on that element?

[jugglinmike]

@CoastalP47 Thanks for the script, but it's not producing an error for me. Maybe it was resolved in one of this project's dependencies? If you have a moment, could you try re-installing Cheerio and seeing if it still fails? If so, the output of npm ls may be relevant.

@binarykitchen that change would fix the immediate problem, but we need to understand the problem before we try to solve it. A failing test case would help us avoid regressions and might even highlight a more fundamental issue.

[rugarcialopez]

I've got the same issue as @binarykitchen when I upgraded Lodash from v2.x to v4.x. Also I've updated cheerio to 0.20.0 and I am still getting the issue. Any ideas??