message: Fail if operation name contains null char.
  The null char is allowed in a string but not in an operation's name, so fail
  parsing in the latter case.
diff: @@ -1726,6 +1726,8 @@ Operation *FunctionParser::parseVerboseOperation(
  auto name = getToken().getStringValue();
  if (name.empty())
  return (emitError("empty operation name is invalid"), nullptr);
  + if (name.find('\0') != StringRef::npos)
  + return (emitError("null character not allowed in operation name"), nullptr);
  consumeToken(Token::string);
  