En mi caso el error se producjo al ejecutar gulp serve para probar un Webpart.

Error: Missing binding C:\holamundo\node_modules\node-sass\vendor\win32-x64-64\binding.node
Node Sass could not find a binding for your current environment: Windows 64-bit with Node.js 10.x

Found bindings for the following environments:
– Windows 64-bit with Node.js 12.x

This usually happens because your environment has changed since running `npm install`.
Run `npm rebuild node-sass` to download the binding for your current environment.

Si ejecutamos la posible solución como indica el mensaje:

npm rebuild node-sass

Como esperaba… no se corregirá el error. Para corregirlo realizar mejor la instalación de nuevo con:

npm install node-sass