"strict" mode that throws when undefined values found

[simlu]

We would love a "strict" option where the library raises when an unknown value is found.

Use case is that often objects get composed directly as a parameter for objectHash. Hence it's hard to get visibility into what is actually hashed. Raising on undefined would ensure that at least something meaningful was put into the object before hashing it.

[simlu]

I realize now that my suggestion was silly, since this library hashes absolutely everything it can get its hand on :) So there will always be something undefined.

What makes sense though it to check if there are any "real" values that are undefined.

I've started working on that in this pr: https://github.com/blackflux/object-hash-strict/pull/3/files