test: add onerror test cases to policy

Increase test coverage of lib/internal/policy/manifest.js

PR-URL: https://github.com/nodejs/node/pull/35797
Refs: https://coverage.nodejs.org/coverage-642f2064c06793b7/lib/internal/policy/manifest.js.html#L60
Refs: https://coverage.nodejs.org/coverage-642f2064c06793b7/lib/internal/policy/manifest.js.html#L146


Reviewed-By: Ben Coe <bencoe@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>