* Use `global.hasOwnProperty(ident)`, rather than `global[ident] !== undefined`,
to avoid classifying references to globals as free variables. Surprise(!!),
the prior logic wouldn't work for `undefined` itself... 😒
* Expand this check to include the built-in Node.js module variables, namely
`__dirname`, `__filename`, `exports`, `module`, and `require`, so that
references to them don't get classified as serializable free variables either.
* Place catch variables in scope, so that `catch (err) { ... }` won't yield
free variables for references to `err` within `...`.
* Place recursive function definitions into the top-level `var`-like scope of
variables so that we don't consider references to them free.
* Harden all error pathways in the native C++ add-on so that we terminate
anytime an exception is in-flight, rather than limping along and making
things worse...