Tailwind npm run dev error

Tailwind CSS is not generating because I can't run

npm run dev

I followed the steps explained in laravel.com/docs/8.x/mix#tailwindcss documentation but I get the following error every time I run the command.

ERROR in ./resources/css/app.css
Module build failed (from ./node_modules/css-loader/index.js):
ModuleBuildError: Module build failed (from ./node_modules/postcss-loader/src/index.js):
TypeError: getProcessedPlugins is not a function

My resources/css/app.css file looks like this

@tailwind base;
@tailwind components;
@tailwind utilities;