TfLiteTensor* GetVariableInput(TfLiteContext* context, const TfLiteNode* node,
                               int index) {
  TfLiteTensor* tensor = GetMutableInput(context, node, index);
  if (tensor == nullptr) return nullptr;
  return tensor->is_variable ? tensor : nullptr;
}
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.