Please try the following

sudo apt-get remove nodejs nodejs-legacy nodered

after that

curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -
sudo apt-get install -y nodejs
sudo npm install -g npm@latest

after that enter in the repository with

cd MagicMirror

If have not install MM, use this from github

 bash -c "$(curl -sL https://raw.githubusercontent.com/MichMich/MagicMirror/master/installers/raspberry.sh)"

then install and run the app with

npm install && npm start

This method worked for me.

Credit: @NoNameRo