This is a problem with npm. You could try using yarn instead, but it's not something that nodebb can fix.
Facebook flike button installation
Re: Anyone Know Any?
I tried to follow this how-to and implement the same. It was a partial success.
I placed it in Appearance -> Custom HTML and CSS -> Custom Header
(The instructions mentioned that I need to add that to header.tpl in theme. Where to find it?)
and the second part in Extend -> Global Footer.
Am I doing right?