Added try/catch block to main().

examples/graph_labeling_ex.cpp

@@ -170,6 +170,8 @@ void make_training_examples(
 
 int main()
 {
+    try
+    {
         // Get the training samples we defined above.
         dlib::array<graph_type> samples;
         std::vector<std::vector<bool> > labels;
@@ -244,5 +246,11 @@ int main()
         temp = labeler(g);
         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;
+    }
 }