Node.js / Angular : permissions problems

After running the following:

$sudo n stable

I got this version response for Node:

$ node -v
v8.6.0

I then ran:

$npm install -g @angular/cli

but got permission errors which suggested I run the command  as root.
 
So, I tried:

$sudo su
(added my password)

$npm install -g @angular/cli
but get bad sounding warnings...



I killed the process, but need to get Angular installed. What can I do?

I get the following error when I try and start the server, whether I am root or have exited root:

sh-3.2# ng serve
module.js:529
    throw err;
    ^

Error: Cannot find module '@ngtools/json-schema'
    at Function.Module._resolveFilename (module.js:527:15)
    at Function.Module._load (module.js:476:23)
    at Module.require (module.js:568:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/usr/local/lib/node_modules/@angular/cli/models/config/config.js:7:23)
    at Module._compile (module.js:624:30)
    at Object.Module._extensions..js (module.js:635:10)
    at Module.load (module.js:545:32)
    at tryModuleLoad (module.js:508:12)
    at Function.Module._load (module.js:500:3)

Is this an Old version of Node??