Check NodeArg has name in ORT formal model load (#27297)

### Description
<!-- Describe your changes. -->
Check for invalid node arg when loading ORT format model. A node arg
would always have a valid string in an ORT created model so this
requires manual editing of the model to make it invalid.

### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->

Author: skottmckay

onnxruntime/core/graph/graph.cc

@@ -6483,7 +6483,9 @@ common::Status Graph::LoadFromOrtFormat(const onnxruntime::fbs::Graph& fbs_graph
       ORT_RETURN_IF(nullptr == fbs_value_info, "NodeArg is missing. Invalid ORT format model.");
       NodeArgInfo node_arg_info;
       ORT_RETURN_IF_ERROR(fbs::utils::LoadValueInfoOrtFormat(*fbs_value_info, node_arg_info));
-      node_args_[fbs_value_info->name()->str()] = std::make_unique<NodeArg>(std::move(node_arg_info));
+      const auto* name = fbs_value_info->name();
+      ORT_RETURN_IF(name == nullptr, "NodeArg name is missing. Invalid ORT format model.");
+      node_args_[name->str()] = std::make_unique<NodeArg>(std::move(node_arg_info));
     }
   }
 

onnxruntime/test/framework/ort_model_only_test.cc

@@ -592,6 +592,16 @@ TEST(OrtModelOnlyTests, GithubIssue17000) {
   RunOrtModel(test_info);
 }
 
+// ICM 31000000518041.
+TEST(OrtModelOnlyTests, NullNodeArgNameCheck) {
+  auto ort_file = ORT_TSTR("testdata/icm-31000000518041.ort");
+
+  SessionOptions so;
+  InferenceSessionWrapper session_object{so, GetEnvironment()};
+  ASSERT_STATUS_NOT_OK_AND_HAS_SUBSTR(session_object.Load(ort_file),
+                                      "NodeArg name is missing. Invalid ORT format model.");
+}
+
 #if !defined(DISABLE_ML_OPS)
 // test that we can deserialize and run a previously saved ORT format model
 // for a model with sequence and map outputs