Fix 78: Serializer.encode throws for null and undefined

[nobrayner]

This resolves #78.

This does diverge from previous behavior by encoding null.

[nobrayner]

I made the decision to encode null based on my own usage: Retrieving data using Prisma ORM in which nullable database columns are returned as null.

I see it as too much maintenance effort to have to convert each nullable column into an Option, especially in an existing codebase where most usages expect T | null as the type.

This approach also brings encode in line with decode, which explicitly handles parsing null.

[bloodyowl]

thanks for your PR! made a small comment

[bloodyowl]

let's maybe rather use the following to maximize browser compatibility

if (value == null) {
  return value
}

[nobrayner]

It's been a while since I had to think about syntax support of older browsers! 😅

I had a niggling that the Typescript compiler actually compiled out optional chaining - depending on the build target - and ran a test build. It did indeed turn the optional chaining into the following:

null==n?n:"string"==typeof n[o]

Then to really satisfy my curiosity, I tried your suggestion and it actually compiled to the exact same output!

[bloodyowl]

thanks for your PR! available in v2.3.1