Incorrect `reportWebpackWarnings` usage

Description

gatsby develop works fine but gatsby build throws error failed Building production JavaScript and CSS bundles

failed Building production JavaScript and CSS bundles - 10.208s

 ERROR #98123  WEBPACK

Generating JavaScript bundles failed

Cannot read property 'split' of undefined

Repo Link: https://github.com/rnmKeshav/portfolio

Steps to reproduce

npm install
npm run build

Expected result

Build should pass successfully

Actual result

> gatsby build

success open and validate gatsby-configs - 0.053s
success load plugins - 0.449s
success onPreInit - 0.021s
success initialize cache - 0.004s
success copy gatsby files - 0.056s
success onPreBootstrap - 0.013s
success createSchemaCustomization - 0.008s
success Checking for changed pages - 0.001s
success source and transform nodes - 0.194s
success building schema - 0.294s
info Total nodes: 127, SitePage nodes: 1 (use --verbose for breakdown)
success createPages - 0.003s
success Checking for changed pages - 0.001s
success createPagesStatefully - 0.041s
success update schema - 0.044s
success onPreExtractQueries - 0.001s
success extract queries from components - 3.498s
success write out redirect data - 0.005s
success Build manifest and related icons - 0.040s
success onPostBootstrap - 0.044s
info bootstrap finished - 6.547s
success run page queries - 0.017s - 5/5 298.88/s
success write out requires - 0.005s
failed Building production JavaScript and CSS bundles - 10.208s

 ERROR #98123  WEBPACK

Generating JavaScript bundles failed

Cannot read property 'split' of undefined


npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! portfolio@1.0.0 build: `gatsby build`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the portfolio@1.0.0 build script.

Environment

System: OS: macOS 11.3.1 CPU: (12) x64 Intel® Core™ i7-9750H CPU @ 2.60GHz Shell: 5.8 - /bin/zsh Binaries: Node: 14.15.0 - ~/.nvm/versions/node/v14.15.0/bin/node npm: 6.14.8 - ~/.nvm/versions/node/v14.15.0/bin/npm Languages: Python: 2.7.16 - /usr/bin/python Browsers: Chrome: 90.0.4430.212 Safari: 14.1 npmPackages: gatsby: 3.2.1 => 3.2.1 gatsby-cli: 3.5.0 => 3.5.0 gatsby-plugin-google-analytics: 3.3.0 => 3.3.0 gatsby-plugin-image: 1.3.0 => 1.3.0 gatsby-plugin-manifest: 3.5.0 => 3.5.0 gatsby-plugin-react-helmet: 4.5.0 => 4.5.0 gatsby-plugin-sass: 4.3.0 => 4.3.0 gatsby-plugin-sharp: 3.3.0 => 3.3.0 gatsby-source-filesystem: 3.3.0 => 3.3.0 gatsby-transformer-sharp: 3.3.0 => 3.3.0 npmGlobalPackages: gatsby-cli: 3.5.0

[KyleAMathews]

I put up a PR which should fix the issue https://github.com/gatsbyjs/gatsby/pull/31489

[github-actions[bot]]

Hiya!

This issue has gone quiet. Spooky quiet. 👻

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