Added try/catch block to main().

examples/graph_labeling_ex.cpp

@@ -169,6 +169,8 @@ void make_training_examples(
 // ----------------------------------------------------------------------------------------
 
 int main()
+{
+    try
     {
         // Get the training samples we defined above.
         dlib::array<graph_type> samples;
@@ -245,4 +247,10 @@ int main()
         for (unsigned long i = 0; i < temp.size(); ++i)
             cout << " " << i << ": " << temp[i] << endl;
     }
+    catch (std::exception& e)
+    {
+        cout << "Error, an exception was thrown!" << endl;
+        cout << e.what() << endl;
+    }
+}