Use existing error handling utilities and appropriate error mechanisms instead of implementing manual error handling logic. This reduces code complexity, improves maintainability, and leverages well-tested library functions. For regex operations, prefer functions like `pmatch_noerr` that handle errors automatically: ```ocaml (* Instead of manual error handling *) match Pcre2_.pmatch ~rex:url_regex config_path with | Ok true -> true | Ok false -> false | Error err -> Log.warn (fun m -> m "Error Validation URL: %a" pp_error err); false (* Use built-in error handling *) let is_url config_path = Pcre2_.pmatch_noerr ~rex:url_regex config_path ``` For impossible cases, choose appropriate mechanisms: use `assert false` for truly impossible conditions, provide clear error messages for invalid input ("at least one target required" rather than "bug: no valid target"), or refactor to eliminate impossible cases entirely. For conditional error handling, structure logic clearly with explicit branching rather than complex nested error propagation.