(node:557) UnhandledPromiseRejectionWarning: Error: unable to get local issuer certificate

[RobKohr]

I just installed with npm install ytdl-core@latest, created an index.js that contains the "Usage" example in the readme, and ran

 % node index.js
(node:557) UnhandledPromiseRejectionWarning: Error: unable to get local issuer certificate
    at TLSSocket.onConnectSecure (_tls_wrap.js:1515:34)
    at TLSSocket.emit (events.js:400:28)
    at TLSSocket._finishInit (_tls_wrap.js:937:8)
    at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:709:12)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:557) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:557) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

[TimeForANinja]

looks like a problem with your local certificate chain
other tools like youtubedl and maybe even chrome should have similar problems
sorry but we can't help you with that