It may be that forcing handling at every call tends to makes code verbose, and devs insensitized to bad practice. And the diagnostic Rust provided seems pretty garbage.

There is bad practice here too -- config failure manifesting as request failure, lack of failing to safe, unsafe rollout, lack of observability.

Back to language design & error handling. My informed view is that robustness is best when only major reliability boundaries need to be coded.

This the "throw, don't catch" principle with the addition of catches on key reliability boundaries -- typically high-level interactions where you can meaningfully answer a failure.

For example, this system could have a total of three catch clauses "Error Loading Config" which fails to safe, "Error Handling Request" which answers 5xx, and "Socket Error" which closes the HTTP connection.