TypeError: Ajv is not a constructor

[vertic4l]

Bug report

Actual Behavior

After upgrading from version 0.11.2 (ya i'm late) to 2.6.0 of mini-css-extract-plugin we notice build issues:

TypeError: Ajv is not a constructor
at Object.<anonymous> (/Sites/frontend-portal/src/node_modules/mini-css-extract-plugin/node_modules/schema-utils/dist/validate.js:66:13)

Expected Behavior

Well, you know what is expected. I've looked into the source of validate.js and seems to be okay, but the error exists.

How Do We Reproduce?

I'm not sure, we have the latest versions of webpack, typescript and mini-css-extract-plugin and it fails to build.
So maybe have the same?

Please paste the results of npx webpack-cli info here, and mention other relevant information

System:
    OS: macOS 11.6.4
    CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 242.55 MB / 16.00 GB
  Binaries:
    Node: 17.7.1 - /usr/local/bin/node
    npm: 8.5.2 - /usr/local/bin/npm
  Browsers:
    Chrome: 99.0.4844.83
    Firefox: 84.0.2
    Safari: 15.3
  Packages:
    copy-webpack-plugin: ^6.2.1 => 6.3.0 
    css-loader: ^3.4.2 => 3.6.0 
    esbuild-loader: ^2.18.0 => 2.18.0 
    file-loader: ^5.0.2 => 5.1.0 
    html-webpack-harddisk-plugin: ^2.0.0 => 2.0.0 
    html-webpack-plugin: ^5.3.2 => 5.3.2 
    postcss-loader: ^4.0.2 => 4.2.0 
    react-hot-loader: ^4.12.18 => 4.13.0 
    sass-loader: 12.3.0 => 12.3.0 
    script-ext-html-webpack-plugin: ^2.1.4 => 2.1.5 
    style-loader: ^1.2.1 => 1.3.0 
    terser-webpack-plugin: ^5.3.1 => 5.2.4 
    thread-loader: ^3.0.0 => 3.0.1 
    url-loader: ^3.0.0 => 3.0.0 
    webpack: ^5.54.0 => 5.70.0 
    webpack-bundle-analyzer: ^4.0.0 => 4.0.0 
    webpack-cli: ^4.8.0 => 4.9.2 
    webpack-dev-server: ^4.3.0 => 4.7.4 

[harish-sethuraman]

Can you once try removing node_modules and re-installing? rm -rf node_modules && yarn install?

[vertic4l]

@harish-sethuraman i already tried this but nothing changed.

[alexander-akait]

You have outdated version of Ajv, they have bug with deps, we can't fix it here

[vertic4l]

npm install --save-dev ajv fixes it. thanks guys

[spacenate]

FWIW, it seems npm up ajv will update the sub-dependency in your package-lock.json, even without explicitly installing ajv as a dependency.