prefer built-in error utilities

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:

(* 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.