message: Fixed the warning in the lstm.cc file
  Removed warnings from the file
diff: @@ -840,6 +840,8 @@ void* Init(TfLiteContext* context, const char* buffer, size_t length) {
  return full::Init(context, buffer, length);
  case kTfLiteLSTMBasicKernel:
  return basic::Init(context, buffer, length);
  + default:
  + return nullptr;
  }
  }
  void Free(TfLiteContext* context, void* buffer) {
  @@ -855,6 +857,8 @@ TfLiteStatus Prepare(TfLiteContext* context, TfLiteNode* node) {
  return full::Prepare(context, node);
  case kTfLiteLSTMBasicKernel:
  return basic::Prepare(context, node);
  + default:
  + return kTfLiteError;
  }
  }
  @@ -865,6 +869,8 @@ TfLiteStatus Eval(TfLiteContext* context, TfLiteNode* node) {
  return full::Eval(context, node);
  case kTfLiteLSTMBasicKernel:
  return basic::Eval(context, node);
  + default:
  + return kTfLiteError;
  }
  }
  