check for sio errors

sndlock.cpp

@@ -88,6 +88,12 @@ static void dsp_thread()
               std::cout << buf_in[i] << " ";
             std::cout << std::endl;
         }
+
+        if(sio_eof(hdl)) {
+            std::cerr << "sound I/O error" << std::endl;
+            sio_close(hdl);
+            return;
+        }
     }
 
     sio_stop(hdl);