display error on failure to load .obj file

wfobj-view.cc

@@ -68,7 +68,11 @@ Viewer::Viewer(const char * filename)
 {
 	m_dist = 5.0;
 	m_dragging = false;
-	m_obj.load(filename);
+	if (!m_obj.load(filename))
+    {
+        cerr << "Error loading " << filename << endl;
+        exit(1);
+    }
 	
 	/* Print out the object's size */
 	const float * aabb = m_obj.getAABB();