function checkSourceValue(source, importer) {
    if (source == null) { return; } //?

    // handle ignore
    if (ignoreRegExps.some((re) => re.test(String(source.value)))) { return; }

    // fire visitor
    visitor(source, importer);
  }
@type {(source: undefined | null | import('estree').Literal, importer: Parameters<typeof visitor>[1]) => void}