Error in running 'npm install' after creating an express app - node.js

Question

I ran: npm install npm install -g express-generator
-> express <name> -> npm install which gave me this error:
npm WARN deprecated jade#1.11.0: Jade has been renamed to pug, please install the latest version of pug instead of jade
npm WARN deprecated transformers#2.1.0: Deprecated, use jstransformer
npm WARN deprecated constantinople#3.0.2: Please update to at least constantinople 3.1.1
npm ERR! code EPERM
npm ERR! syscall rename
npm ERR! path <path>
npm ERR! dest <path>
npm ERR! errno -4048
npm ERR! Error: EPERM: operation not permitted, rename '<path>' -> '<path>'
npm ERR! [OperationalError: EPERM: operation not permitted, rename '<path>' -> '<path>'] {
npm ERR! cause: [Error: EPERM: operation not permitted, rename '<path>' -> '<path>'] {
npm ERR! errno: -4048,
npm ERR! code: 'EPERM',
npm ERR! syscall: 'rename',
npm ERR! path: '<path>',
npm ERR! dest: '<path>'
npm ERR! },
npm ERR! errno: -4048,
npm ERR! code: 'EPERM',
npm ERR! syscall: 'rename',
npm ERR! dest: '<path>',
npm ERR! parent: '<name>'
npm ERR! }
npm ERR!
npm ERR! It's possible that the file was already in use (by a text editor or antivirus),
npm ERR! or that you lack permissions to access it.
npm ERR!
npm ERR! If you believe this might be a permissions issue, please double-check the
npm ERR! permissions of the file and its containing directories, or try running
npm ERR! the command again as root/Administrator.
package-lock.json has been created. Is this an error to worry about? If yes how to solve this issue? I did npm install pug --save which too gave me 4 vulnerabilities (3 low, 1 critical)
. But when I created an express app using express name, it scaffold out a views folder with files such as: 'error.jade', etc. Now after installing 'pug', do I need to change something else in my files too, since those initial codes were default in the app created by latest express-generator?