What does the 'unable to get local issuer certificate' error in Node.js `fetch` mean?

This error in Node.js `fetch` indicates a problem with verifying the SSL/TLS certificate of the server you are trying to connect to. Specifically, it means your Node.js environment doesn't trust the certificate authority (CA) that signed the server's SSL certificate. This often happens when using self-signed certificates or certificates signed by a CA not included in your system's trusted root certificates.