Validation — Fail Loud

Configuration is foundational, so Configuard treats a corrupt row as a hard error: the constructor throws immediately rather than logging a warning and building a partial object. It throws when:

• a value can’t be parsed to its declared type (e.g. bad json/hexadecimal/time/date, or a number that resolves to NaN);
• a ${...} template reference is missing or circular;
• an item is malformed — an invalid accessor/listType/type, or a non-string key.

try {
  const cfg = new Configuard(rows, { accessor: AccessorType.SYSTEM });
  // use cfg.data / cfg.get(...)
} catch (err) {
  // e.g. 'Value "abc" of key "port" is not a valid number.'
  // the original parser error (when any) is available as err.cause
}

parseFlat() likewise throws on missing/circular templates, a missing option list, or a value outside its option list.

ConfiguardError

Every failure throws a ConfiguardError (exported from the package root), so consumers can react to a configuration fault specifically:

import { Configuard, ConfiguardError } from 'configuard';

try {
  new Configuard(rows, { accessor: AccessorType.SYSTEM });
} catch (err) {
  if (err instanceof ConfiguardError) {
    err.key;   // the offending config item key, when known
    err.cause; // the underlying error (e.g. the parser failure), when any
  }
}

key and cause are what make these errors actionable: key points at the exact row to fix, and cause carries the lower-level error when the fault came from the value parser or a crypto hook.