Don't segfault when sound is not available

diff --git a/src/Instrumentation/mk_viii.hxx b/src/Instrumentation/mk_viii.hxx
index 60a3f94588c83593e4396dccc9bcf0f05ee92596..47b76440f448d5aa17a0dad41cc23b57b8e93386 100755 (executable)
--- a/src/Instrumentation/mk_viii.hxx
+++ b/src/Instrumentation/mk_viii.hxx
@@ -745,10 +745,10 @@ public:
        inline SampleElement (SGSoundSample *sample, double volume = 1.0)
          : _sample(sample), _volume(volume) { silence = false; }
 
-       virtual inline void play (double volume) { set_volume(volume); _sample->play_once(); }
-       virtual inline void stop () { _sample->stop(); }
-       virtual inline bool is_playing () { return _sample->is_playing(); }
-       virtual inline void set_volume (double volume) { _sample->set_volume(volume * _volume); }
+        virtual inline void play (double volume) { if (_sample) { set_volume(volume); _sample->play_once(); } }
+       virtual inline void stop () { if (_sample) _sample->stop(); }
+        virtual inline bool is_playing () { return _sample ? _sample->is_playing() : false; }
+       virtual inline void set_volume (double volume) { if (_sample) _sample->set_volume(volume * _volume); }
       };
 
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