> We have both exceptions and 2 special marker types (null, undefined). Different libraries will use different methods to signify errors. See Rust for how to do

> We have both exceptions and 2 special marker types (null, undefined). Different libraries will use different methods to signify errors. See Rust for how to do this well. This is in part because JS’s exceptions support is the worst: catch clauses can’t be filtered by type so you have to catch/filter/rethrow, and before ES6 subtyping Error was essentially impossible. So even if you are fine with exceptions, you don’t want to use them in JS. Even more so before async proper as they obviously did not work correctly through callback chains.