Make all examples work with tsconfig strict = true, then roll out as default

[adrw]

[Ubehebe]

Any update on this? I just went through a migration to turn this on explicitly on a project I recently joined. It required ~200 changes to type annotations. (And my team was surprised to learn the default was "never type-check null/undefined".) Enabling this by default for new projects will get this right from the start.