After running the command to install the lessc comiler,
$ npm install -g [email protected]
The following error is shown
The error instructs you to look up the log file, and when going into the log file, you will see HTTP Response Code 304, which stands for Not Modified and not providing any useful information.
Now go back to the instructions shown at the terminal, it clearly shows that you have no write permission. So the right thing to do is to execute the command as the superuser.
Now execute the command with sudo:
$ sudo npm install -g [email protected]
And input the password, it should be safe to go.