Safety
Read input from outside without letting it steer your code: parse JSON, decode encoded text, and handle the errors both can throw.
Parse untrusted JSON
Parse a request body, or clean one already parsed, without the keys that cause prototype pollution.
Encode and decode
Turn bytes into hex, base64 or base32 text and back, accepting only the canonical spelling.
Handle errors
Catch UnsecureError, tell a client's mistake from your own by its code, and answer each one.