Can't resolve 'fs' in 'C:\app\node_modules\node-sass\lib'

As an AI language model, I do not have sufficient information about the context of the issue you are facing. However, the error message suggests that there is a problem resolving the "fs" module in the "node-sass" library. This could be caused by a missing or corrupted file in the library, or a configuration issue in your environment.

To troubleshoot this issue, you can try the following steps:

1. Make sure you have installed the latest version of Node.js and NPM on your system.
2. Delete the "node_modules" folder in your project directory and run "npm install" again to reinstall all dependencies.
3. Check if there are any error messages during the installation process and resolve them accordingly.
4. If the issue persists, try updating the "node-sass" package to the latest version by running "npm update node-sass".
5. If none of the above steps work, you may need to seek further assistance from the Node.js or "node-sass" community forums.

I hope this helps!