Unexpected token u in JSON at position 0

[receter]

I updated my project to Gatsby 3 and can’t start the dev server unless I disable gatsby-plugin-favicon.

I am on Windows with WSL 2, this is the error that comes up if I try to start:

verbose Transition to "runningQueries" > "waitingForJobs"
verbose Transition to "runningQueries" > "done"
verbose Transition to "startingDevServers"

 ERROR 

(node:8994) [DEP_WEBPACK_COMPILATION_CACHE] DeprecationWarning: Compilation.cache was removed in favor of Compilation.getCache()
(Use `node --trace-deprecation ...` to show where the warning was created)


 ERROR 

(node:8994) [DEP_WEBPACK_COMPILATION_OPTIMIZE_CHUNK_ASSETS] DeprecationWarning: optimizeChunkAssets is deprecated (use Compilation.hooks.processAssets instead and use one of
Compilation.PROCESS_ASSETS_STAGE_* as stage option)

⠦ Building development bundle
/home/.../node_modules/yoga-layout-prebuilt/yoga-layout/build/Release/nbind.js:53
        throw ex;
        ^

SyntaxError: Unexpected token u in JSON at position 0
    at JSON.parse (<anonymous>)
    at /home/.../node_modules/favicons-webpack-plugin/lib/compiler.js:115:23
    at /home/.../node_modules/webpack/lib/Compiler.js:534:11
    at /home/.../node_modules/webpack/lib/Compiler.js:1089:17
    at Hook.eval [as callAsync] (eval at create (/home/.../node_modules/webpack/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:6:1)
    at Hook.CALL_ASYNC_DELEGATE [as _callAsync] (/home/.../node_modules/webpack/node_modules/tapable/lib/Hook.js:18:14)
    at /home/.../node_modules/webpack/lib/Compiler.js:1085:33
    at /home/.../node_modules/webpack/lib/Compilation.js:2496:11
    at Hook.eval [as callAsync] (eval at create (/home/.../node_modules/webpack/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:6:1)
    at Hook.CALL_ASYNC_DELEGATE [as _callAsync] (/home/.../node_modules/webpack/node_modules/tapable/lib/Hook.js:18:14)
    at /home/.../node_modules/webpack/lib/Compilation.js:2489:38
    at eval (eval at create (/home/.../node_modules/webpack/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:15:1)
    at /home/.../node_modules/webpack/lib/Compilation.js:468:10
    at /home/.../node_modules/webpack/lib/SourceMapDevToolPlugin.js:546:10
    at /home/.../node_modules/neo-async/async.js:2830:7
    at Object.each (/home/.../node_modules/neo-async/async.js:2857:9)```

My packages:

```  "dependencies": {
    "@wyze/gatsby-source-graphql": "^1.2.0",
    "gatsby": "^3.3.1",
    "gatsby-cli": "^3.3.0",
    "gatsby-plugin-env-variables": "^2.1.0",
    "gatsby-plugin-favicon": "^3.1.6",
    "gatsby-plugin-google-tagmanager": "^3.3.0",
    "gatsby-plugin-i18n": "^1.0.1",
    "gatsby-plugin-netlify": "^3.3.0",
    "gatsby-plugin-react-helmet": "^4.3.0",
    "gatsby-plugin-sass": "^4.3.0",
    "gatsby-source-filesystem": "^3.3.0",
    "gatsby-source-iubenda": "^1.0.2",
    "gatsby-source-strapi": "0.0.12",
    "intl": "^1.2.5",
    "node-sass": "^4.14.1",
    "prop-types": "^15.7.2",
    "react": "^17.0.2",
    "react-dom": "^17.0.2",
    "react-helmet": "^6.1.0",
    "react-intl": "^4.7.6",
    "react-player": "^2.9.0",
    "react-slick": "^0.23.2",
    "typeface-roboto": "0.0.54",
    "universal-cookie": "^3.1.0"
  },
  "resolutions": {
    "graphql": "^15.4.0",
    "graphql-compose": "^7.25.0",
    "webpack": "^5.24.2"
  },```

[receter]

I did log some variables too:

// Resolve / reject the promise
      if (childCompilation && childCompilation.errors && childCompilation.errors.length) {
        var errorDetails = childCompilation.errors.map(function (error) {
          return error.message + (error.error ? ':\n' + error.error : '');
        }).join('\n');
        reject(new Error('Child compilation failed:\n' + errorDetails));
      } else if (err) {
        reject(err);
      } else {

        console.log(childCompilation.assets);
        console.log(childCompilation.assets[outputName].source());
        console.log(outputName);
        console.log('test');

        resolve({
          outputName: outputName,
          stats: JSON.parse(childCompilation.assets[outputName].source())
        });
      }

Result:

{
  '.iconstats.json': { source: [Function: source], size: [Function: size] }
}
⠀
.iconstats.json
test

[dylan-13]

You'll have more help if you put this issue on Gatsby repo, and like that you'll trigger a problem that they can relate on the doc.

[Clement-Bresson]

I got the same issue with gatsby-plugin-favicon + gatsby v3.
If it can help, I ended up using https://www.gatsbyjs.com/plugins/gatsby-plugin-manifest/ which handles favicon (+ other things) and works well with gatsby v3.