message: Skip processing nil tensors in XNNPACK delegate
  Negative (typically -1) tensor ID indicates omitted input/output tensor
diff: @@ -184,14 +184,18 @@ class Subgraph {
  // All other operators: process all inputs
  for (int k = 0; k < node->inputs->size; k++) {
  const int t = node->inputs->data[k];
  + if (t >= 0) {
  tensors[t] = t;
  }
  }
  + }
  for (int k = 0; k < node->outputs->size; k++) {
  const int t = node->outputs->data[k];
  + if (t >= 0) {
  tensors[t] = t;
  }
  }
  + }
  // Filter out and remove -1 (unused) indexes.
  tensors.erase(std::remove_if(tensors.begin(), tensors.end(),
  [](int i) { return i < 0; }),
  