In preparation to work on enabling
https://www.typescriptlang.org/tsconfig/#strictNullChecks, I fixed all
the issues outside of `web_src` that came up when the option was
enabled. There was also one lint issue in web_src that apparently only
came up with the option enabled, so I fixed that as well.
`isTruthy` is introduced because Typescript has a bug regarding
`filter(Boolean)` which they are seemingly unwilling to fix.
---------
Signed-off-by: silverwind <me@silverwind.io>
Migrate all JS config and tools to TS and fix a number of type issues.
This required Node.js 22.18.0 or greater where [type-stripping was
enabled](https://nodejs.org/en/blog/release/v22.18.0) by default.
Given that Node 22 is the current LTS, I think it's ok to assume that
the user has a recent version of it.
Webpack currently requires the `--disable-interpret` flag to work,
should be fixed eventually with
https://github.com/webpack/webpack-cli/issues/4525.
`fast-glob` is replaced by `fs.globSync`, available in Node 22.0.0 or
greater.
