[feat] cache dummy-proofing

[titanism]

Describe the feature

When cache is retrieved, dependent on the type, if the result is not of the proper type (e.g. it's an Array instead of an Object) then set data = undefined which will cause the cache to be purged/reset. This was a feature we built-in to Forward Email when we used to use dns.promises.Resolver.

Note: this is a super edge case, but is dummy-proofing in case of a bad redis set, or if a developer manually edited the cache value for whatever reason.

Checklist

• [x] I have searched through GitHub issues for similar issues.
• [x] I have completely read through the README and documentation.

[titanism]

Not going to fix as it's unnecessary right now