Errors as return value are a “function color” too (in practice, you need to propagate it upwards the stack and it “contaminates” your code the same way as async

Errors as return value are a “function color” too (in practice, you need to propagate it upwards the stack and it “contaminates” your code the same way as async/await). And in fact it interacts better with async/await (like in Rust) than with channels…