With let outside the try, because that's the intended scope. Insofar as there is a problem I see with that, it's that you can't separate declaration of a single-assignment value (const) from the one allowed assignment, because the ideal solution would be const declared outside the try with the assignment inside.

OTOH var declared inside is a bad solution because it's both misleading as to scope and using a freely-assignable variable for something that's logically single-assignment. Let outside has only one of those problems.