> If a function can fail I want to see it right there on the return type and be forced to handle it on the spot.

Checked exceptions solve this problem. Checked exceptions vs. result sum types aren’t a black and white dichotomy, however. They are rather two points on a design spectrum, where one design axis is how you want to syntactically handle error escalation up the call chain, another axis is how you want to handle destructuring/restructuring of the results, etc.

Unchecked exceptions are still useful for notifying bugs (e.g. precondition violations) instead of aborting the OS process on failed assertions.