docs: @Nonnull
      public JsonToken expectNumber(String message) throws IOException, JsonException {
          if (!hasNext()) {
              throw newParseException("Expected %s (number): Got end of file", message);
          } else {
              if (unreadToken.isInteger() || unreadToken.isDouble()) {
                  JsonToken tmp = unreadToken;
                  unreadToken = null;
                  return tmp;
              }
  
              throw newMismatchException("Expected %s (number): but found '%s'",
                                         message, unreadToken.asString(),
                                         message);
          }
      }