Log exceptions when processing a request

@@ -232,6 +232,8 @@ public class DirectControlServlet extends HttpServlet {
         } catch (Throwable t) {
             response.setStatus(400);
             PrintWriter writer = response.getWriter();
+            Debug.logInfo("Exception processing request", module);
+            Debug.logInfo(t, module);
             while (t != null) {
                 t.printStackTrace(writer);
                 t = t.getCause();