Build Error: HookWebpackError with cssnano-simple

[SmallhillCZ]

Spent a day with this, nothing helps.

This looks very close: vercel/next.js#68476

$ npm run build

> metacity-studio@1.0.1 build
> next build --debug

  ▲ Next.js 14.2.11
  - Environments: .env

   Creating an optimized production build ...
Failed to compile.

HookWebpackError: Cannot read properties of undefined (reading 'length')
    at makeWebpackError (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/webpack/bundle5.js:28:312635)
    at /workspaces/pds-studio/studio/node_modules/next/dist/compiled/webpack/bundle5.js:28:106060
    at eval (eval at create (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/webpack/bundle5.js:13:28858), <anonymous>:44:1)
-- inner error --
TypeError: Cannot read properties of undefined (reading 'length')
    at equals (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/cssnano-simple/index.js:190:9716)
    at dedupeNode (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/cssnano-simple/index.js:190:10143)
    at dedupe (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/cssnano-simple/index.js:190:10378)
    at OnceExit (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/cssnano-simple/index.js:190:10483)
    at LazyResult.runAsync (/workspaces/pds-studio/studio/node_modules/next/node_modules/postcss/lib/lazy-result.js:298:21)
    at async /workspaces/pds-studio/studio/node_modules/next/dist/build/webpack/plugins/css-minimizer-plugin.js:79:44
    at async Span.traceAsyncFn (/workspaces/pds-studio/studio/node_modules/next/dist/trace/trace.js:154:20)
    at async Promise.all (index 16)
    at async /workspaces/pds-studio/studio/node_modules/next/dist/build/webpack/plugins/css-minimizer-plugin.js:67:21
    at async Span.traceAsyncFn (/workspaces/pds-studio/studio/node_modules/next/dist/trace/trace.js:154:20)
caused by plugins in Compilation.hooks.processAssets
TypeError: Cannot read properties of undefined (reading 'length')
    at equals (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/cssnano-simple/index.js:190:9716)
    at dedupeNode (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/cssnano-simple/index.js:190:10143)
    at dedupe (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/cssnano-simple/index.js:190:10378)
    at OnceExit (/workspaces/pds-studio/studio/node_modules/next/dist/compiled/cssnano-simple/index.js:190:10483)
    at LazyResult.runAsync (/workspaces/pds-studio/studio/node_modules/next/node_modules/postcss/lib/lazy-result.js:298:21)
    at async /workspaces/pds-studio/studio/node_modules/next/dist/build/webpack/plugins/css-minimizer-plugin.js:79:44
    at async Span.traceAsyncFn (/workspaces/pds-studio/studio/node_modules/next/dist/trace/trace.js:154:20)
    at async Promise.all (index 16)
    at async /workspaces/pds-studio/studio/node_modules/next/dist/build/webpack/plugins/css-minimizer-plugin.js:67:21
    at async Span.traceAsyncFn (/workspaces/pds-studio/studio/node_modules/next/dist/trace/trace.js:154:20)


> Build failed because of webpack errors