Struck on node.js.npm command keeps giving just one output "Error: EISDIR:illegal operation on a directory, read". .npmrc is not found in directory

Question

I was unable to send e-mail through Node.js. So I googled a few pages. And I saw a command and executed it.

The command was npm config set cafile /path/to/your/cert.pem --global.

Now it ended up giving only one output for all npm commands

Error: EISDIR: illegal operation on a directory, read

I couldn't find .npmrc file anywhere in the parent directory. But I saw one in the project folder and it was empty.