[resynthesize]

> Eg in Typescript you will often still run into bugs caused by malformed JSON that doesn't fit the type declaration, badly or insufficiently typed third party libraries

there's a fantastic typescript library, io-ts (https://github.com/gcanti/io-ts), that provides the ability to declare runtime types variables that you can infer compile time types from that solves exactly this problem. it's deifnitely work taking a close look at if you want to ensure type safety at runtime for data coming from third parties.