message: Fix segfault when Softmax is first in graph
diff: @@ -621,7 +621,8 @@ void ConvertSoftmaxOperator(const Model& model, const SoftmaxOperator& src_op,
  GraphDef* tensorflow_graph) {
  string softmax_input;
  Operator* providing_op = GetOpWithOutput(model, src_op.inputs[0]);
  - if (providing_op->type == OperatorType::kTensorFlowReshape) {
  + if (providing_op != nullptr &&
  + providing_op->type == OperatorType::kTensorFlowReshape) {
  softmax_input = src_op.inputs[0];
  } else {
  // Insert a reshape operator that reduces the dimensions down to the 2 that
  