Error: `libsass` bindings not found in C:\Users\Sergey\WebstormProjects\main-links\node_modules\grunt-sass\node_modules\nod
e-sass\vendor\win32-x64-46\binding.node. Try reinstalling `node-sass`?

запустите

npm rebuild node-sass

This command runs the npm build command on the matched folders. This is useful when you install a new version of node, and must recompile all your C++ addons with the new binary.

(Эта команда полезна после обновления nodejs до новой версии).
npm-rebuild