`Cannot read property 'split' of undefined`

[toriningen]

Version 0.6.4. Initial build has been successful, however on rebuild I've got this exception:

TypeError: Cannot read property 'split' of undefined
    at /opt/app/node_modules/hard-source-webpack-plugin/index.js:923:22
    at Array.forEach (<anonymous>)
    at /opt/app/node_modules/hard-source-webpack-plugin/index.js:914:31
    at Array.forEach (<anonymous>)
    at /opt/app/node_modules/hard-source-webpack-plugin/index.js:886:39
    at <anonymous>

I've altered hard-source-webpack-plugin/index.js to see what's wrong:

     resolveItem.loaders.forEach(function(loader) {
+      console.log(">>>>", loader);
       if (typeof loader === 'object') {
         loader = loader.loader;
       }
       // Loaders specified in a dependency are searched for from the
       // context of the module containing that dependency.
       var loaderMissing = missingCache.loader[JSON.stringify([
         resolveKey[1],
         loader.split('?')[0]  //// <<<< exception is here
       ])];

It seems that for some reason, some loader objects are improperly serialized strings:

Valid loaders printed by the debugging statement above:

>>>> { loader: '/opt/app/node_modules/html-webpack-plugin/lib/loader.js' }
>>>> { loader: '/opt/app/node_modules/offline-plugin/lib/misc/sw-loader.js',
  options: 'json=%7B%22data_var_name%22%3A%22__wpo%22%2C%22loaders%22%3A%5B%5D%2C%22cacheMaps%22%3A%5B%5D%7D' }
>>>> { options: 
   { cacheDirectory: true,
     plugins: [ 'transform-runtime' ],
     presets: [ 'es2015', 'react', 'stage-0' ],
     env: { local: [Object], production: [Object] } },
  ident: 'ref--0-0',
  loader: '/opt/app/node_modules/babel-loader/lib/index.js' }
>>>> { options: 
   { cacheDirectory: true,
     plugins: [ 'transform-runtime' ],
     presets: [ 'es2015', 'react', 'stage-0' ],
     env: { local: [Object], production: [Object] } },
  ident: 'ref--0-0',
  loader: '/opt/app/node_modules/babel-loader/lib/index.js' }

Problematic loader:

>>>> { '0': '/',
  '1': 'o',
  '2': 'p',
  '3': 't',
  '4': '/',
  '5': 'a',
  '6': 'p',
  '7': 'p',
  '8': '/',
  '9': 'n',
  '10': 'o',
  '11': 'd',
  '12': 'e',
  '13': '_',
  '14': 'm',
  '15': 'o',
  '16': 'd',
  '17': 'u',
  '18': 'l',
  '19': 'e',
  '20': 's',
  '21': '/',
  '22': 'o',
  '23': 'f',
  '24': 'f',
  '25': 'l',
  '26': 'i',
  '27': 'n',
  '28': 'e',
  '29': '-',
  '30': 'p',
  '31': 'l',
  '32': 'u',
  '33': 'g',
  '34': 'i',
  '35': 'n',
  '36': '/',
  '37': 'l',
  '38': 'i',
  '39': 'b',
  '40': '/',
  '41': 'm',
  '42': 'i',
  '43': 's',
  '44': 'c',
  '45': '/',
  '46': 'r',
  '47': 'u',
  '48': 'n',
  '49': 't',
  '50': 'i',
  '51': 'm',
  '52': 'e',
  '53': '-',
  '54': 'l',
  '55': 'o',
  '56': 'a',
  '57': 'd',
  '58': 'e',
  '59': 'r',
  '60': '.',
  '61': 'j',
  '62': 's',
  '63': '?',
  '64': '{',
  '65': '"',
  '66': 'S',
  '67': 'e',
  '68': 'r',
  '69': 'v',
  '70': 'i',
  '71': 'c',
  '72': 'e',
  '73': 'W',
  '74': 'o',
  '75': 'r',
  '76': 'k',
  '77': 'e',
  '78': 'r',
  '79': '"',
  '80': ':',
  '81': '{',
  '82': '"',
  '83': 'l',
  '84': 'o',
  '85': 'c',
  '86': 'a',
  '87': 't',
  '88': 'i',
  '89': 'o',
  '90': 'n',
  '91': '"',
  '92': ':',
  '93': '"',
  '94': '/',
  '95': 's',
  '96': 'w',
  '97': '.',
  '98': 'j',
  '99': 's',
  '100': '"',
  '101': ',',
  '102': '"',
  '103': 'e',
  '104': 'v',
  '105': 'e',
  '106': 'n',
  '107': 't',
  '108': 's',
  '109': '"',
  '110': ':',
  '111': 't',
  '112': 'r',
  '113': 'u',
  '114': 'e',
  '115': '}',
  '116': ',',
  '117': '"',
  '118': 'A',
  '119': 'p',
  '120': 'p',
  '121': 'C',
  '122': 'a',
  '123': 'c',
  '124': 'h',
  '125': 'e',
  '126': '"',
  '127': ':',
  '128': '{',
  '129': '"',
  '130': 'l',
  '131': 'o',
  '132': 'c',
  '133': 'a',
  '134': 't',
  '135': 'i',
  '136': 'o',
  '137': 'n',
  '138': '"',
  '139': ':',
  '140': '"',
  '141': '/',
  '142': 'a',
  '143': 'p',
  '144': 'p',
  '145': 'c',
  '146': 'a',
  '147': 'c',
  '148': 'h',
  '149': 'e',
  '150': '/',
  '151': '"',
  '152': ',',
  '153': '"',
  '154': 'n',
  '155': 'a',
  '156': 'm',
  '157': 'e',
  '158': '"',
  '159': ':',
  '160': '"',
  '161': 'm',
  '162': 'a',
  '163': 'n',
  '164': 'i',
  '165': 'f',
  '166': 'e',
  '167': 's',
  '168': 't',
  '169': '"',
  '170': ',',
  '171': '"',
  '172': 'e',
  '173': 'v',
  '174': 'e',
  '175': 'n',
  '176': 't',
  '177': 's',
  '178': '"',
  '179': ':',
  '180': 't',
  '181': 'r',
  '182': 'u',
  '183': 'e',
  '184': ',',
  '185': '"',
  '186': 'd',
  '187': 'i',
  '188': 's',
  '189': 'a',
  '190': 'b',
  '191': 'l',
  '192': 'e',
  '193': 'I',
  '194': 'n',
  '195': 's',
  '196': 't',
  '197': 'a',
  '198': 'l',
  '199': 'l',
  '200': '"',
  '201': ':',
  '202': 'f',
  '203': 'a',
  '204': 'l',
  '205': 's',
  '206': 'e',
  '207': '}',
  '208': '}',
  loader: undefined }

I suppose that hotfix would be to add check like this (until real cause is discovered):

if (typeof loader === 'object') && (loader.loader == null)) {
    const _a = [];
    for (const [k, v] of Object.entries(loader)) {
        _a[k] = v;
    }
    loader = _a.join('');
}

Please let me know if I can provide any additional info on this.

[toriningen]

I've submitted PR #290 with fix.

[williamoliveira]

Having the same problem, with the same problematic plugin (OfflinePlugin)

[mxstbr]

Same issue here! /cc @NekR

[NekR]

Totally not sure why offline-plugin is problematic here. Are there info what hard-source-plugin does and what should be avoided in other plugins where used together?

[williamoliveira]

I am guessing offiline-plugin injects a loader as a string and hard-source-plugin expects an object, or something like that, not sure how webpack works internally

[NekR]

Hmm.. so it might be a webpack 4 thing 🤔Not sure what webpack accepted there previously. Well, if object works in 2-4 versions, then I can change that, no problem.

@mxstbr what version of webpack and offline-plugin are you using?

[mxstbr]

Webpack v2 I think, and the latest offline plugin?

[NekR]

@mxstbr there were some changed is that part of the code, but mainly related to webpack 4. Have you just started using hard-source-plugin and got the error or you were using it, now updated to latest offline-plugin and got the error?

[mxstbr]

Just started using this plugin

[NekR]

@mxstbr okay, I see. Sounds like a long standing error. I'll check today what I can do, maybe I can fix it on my side. Thanks for ccing!

[motin]

I've submitted PR #290 with fix.

Thanks. This issue went away after installing the fixed version from your PR:
npm install --save-dev toriningen/hard-source-webpack-plugin#feature/fix-289

[NekR]

Unfortunately it cannot fix it on my side.

Changing:

result.loaders.push(
  path.join(__dirname, 'misc/runtime-loader.js') +
    '?' + JSON.stringify(data)
);

to

result.loaders.push({
  loader: path.join(__dirname, 'misc/runtime-loader.js') +
    '?' + JSON.stringify(data)
});

Results into errors.

And there is no docs about it, you know, because it's webpack. https://twitter.com/nekrtemplar/status/990215317879173122?s=20