message: Fix ASan error while accessing opcode->custom_name.
diff: @@ -228,17 +228,23 @@ TfLiteStatus InterpreterBuilder::BuildLocalIndexToRegistrationMapping() {
  }
  // If it's an unresolved custom op, allow it for now. It might be resolved
  // by a delegate later.
  + if (!opcode->custom_code()) {
  + error_reporter_->Report(
  + "Operator with CUSTOM builtin_code has no custom_code.\n");
  + return status;
  + }
  + const auto* op_name = opcode->custom_code()->c_str();
  TfLiteRegistration unresolved_op{nullptr,
  nullptr,
  nullptr,
  /*invoke*/ &UnresolvedOpInvoke,
  nullptr,
  BuiltinOperator_CUSTOM,
  - opcode->custom_code()->c_str(),
  + op_name,
  1};
  unresolved_custom_ops_.push_back(unresolved_op);
  registration = &unresolved_custom_ops_.back();
  - has_flex_op_ |= IsFlexOp(registration->custom_name);
  + has_flex_op_ |= IsFlexOp(op_name);
  status = kTfLiteOk;
  }
  flatbuffer_op_index_to_registration_.push_back(registration);
  