Were you thinking of doing this in eslint-config-wikimedia (or eslint-plugin-mediawiki)?

@Jdforrester-WMF at the moment, we're just looking if there's a tool that will find the kind of problems we've noticed.

I did some checks and for linting I think it will only help us if we used typescript with rules like @typescript-eslint/await-thenable, @typescript-eslint/require-await and @typescript-eslint/no-floating-promises.