Payloads
(binaries, plus source tarballs that nvm compiles and runs at install time) are trusted by construction,
since nvm exists to build and run them;
parsed metadata (index.tab, SHASUMS, LTS codenames) is not,
and must never reach a command evaluator,
an awk/sed program body,
or an unvalidated filesystem path.
This records why the existing version-string and checksum hardening exists,
and scopes a malicious payload from a configured mirror as out of scope:
no privilege boundary is crossed.
