Unable to build with version 2.5.0

[sheshanth]

Bug report

Actual Behavior

Unable to build with the new miniCssExtractPlugin version 2.5.0

error: MiniCssExtractPlugin is not a constructor.

build is successful while using the previous version 2.4.7

Expected Behavior

Expected to build successfully.

How Do We Reproduce?

repo link: https://github.com/sheshanth/mini-css-plugin.git

1. clone repo using the link above.
2. install dependencies yarn install or npm install
3. run build yarn buildor npm build

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

[webpack-cli] Failed to load 'E:\development\test\webpack.config.js' config
[webpack-cli] TypeError: MiniCssExtractPlugin is not a constructor
at Object. (E:\development\test\webpack.config.js:18:5)
at Module._compile (internal/modules/cjs/loader.js:1085:14)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
at Module.load (internal/modules/cjs/loader.js:950:32)
at Function.Module._load (internal/modules/cjs/loader.js:790:14)
at Module.require (internal/modules/cjs/loader.js:974:19)
at require (internal/modules/cjs/helpers.js:92:18)
at WebpackCLI.tryRequireThenImport (E:\development\test\node_modules\webpack
-cli\lib\webpack-cli.js:244:16)
at loadConfigByPath (E:\development\test\node_modules\webpack-cli\lib\webpac
k-cli.js:1710:30)
at WebpackCLI.loadConfig (E:\development\test\node_modules\webpack-cli\lib\w
ebpack-cli.js:1830:36)
error Command failed with exit code 2.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this comm
and.

[sheshanth]

duplicate: #896