NULL values should be mapped to undefined

[malthe]

TypeScript prefers undefined to null because it means missing value and as a property, there is syntax to support this – the ?-operator.

We should convert the SQL NULL value into undefined instead of null for this reason.

Note that JSON data, we'll always have null for a null value (there is no undefined in JSON, those properties are simply dropped).

[nitwhiz]

In the same guide:

These are Coding Guidelines for Contributors to TypeScript. This is NOT a prescriptive guideline for the TypeScript community. These guidelines are meant for contributors to the TypeScript project's codebase. We have chosen many of them for team consistency.

The optional chaining operator supports both, undefined and null.

SQL NULL should be null. A value not being there (because the select is missing it or something else) is undefined. null is a real value we can type with this, like string or number. If you use null for both cases, it's hard to track the issue of a missing column down.

[malthe]

@nitwhiz I have reverted the commits directly to the master branch, moving them into a pull request (linked here) for further discussion.