message: Handle error in Unicode normalization, otherwise failing to load NFKC dereferences a nullptr and crashes
diff: @@ -379,6 +379,15 @@ std::string ReaderUtil::Normalize(const std::string &str) {
  UErrorCode err = U_ZERO_ERROR;
  std::string res;
  const icu::Normalizer2* norm = icu::Normalizer2::getNFKCInstance(err);
  + if (U_FAILURE(err)) {
  + static bool err_reported = false;
  + if (!err_reported) {
  + fprintf(stderr, "Normalizer2::getNFKCInstance failed (%s). \"nrm\" is probably missing in the ICU data file. Unicode normalization will not work!\n", u_errorName(err));
  + err_reported = true;
  + }
  + uni.toUTF8String(res);
  + return res;
  + }
  icu::UnicodeString f = norm->normalize(uni, err);
  if (U_FAILURE(err)) {
  uni.toUTF8String(res);
  