Answers for "Unexpected end of JSON input while parsing near '...ent: https://openpgpj'"

npm ERR! Unexpected end of JSON input while parsing near '...r\nComment: https://o'

npm cache clean --force
npm install -g @angular/cli

Unexpected end of JSON input while parsing near

Open Windows Powershell as admin
npm cache clean --force
solved the problem for me

Alternative : You can use yarn instead
npm install -g yarn