protect auditioner against unloaded keyswitches

engine/auditioner.py

@@ -165,11 +165,11 @@ class Auditioner(object):
     def triggerNoteOnCallback(self, timestamp, channel, pitch, velocity):
         """args are: timestamp, channel, note, velocity.
          consider to change eventloop.slowConnect to fastConnect. And also disconnect in self.disable()"""
-        if self.idKey:
+        if self.idKey and self.instrumentLayer:
             self.parentData.instrumentMidiNoteOnActivity(self.idKey, pitch, velocity)
 
     def triggerNoteOffCallback(self, timestamp, channel, pitch, velocity):
         """args are: timestamp, channel, note, velocity.
         consider to change eventloop.slowConnect to fastConnect. And also disconnect in self.disable()"""
-        if self.idKey:
+        if self.idKey and self.instrumentLayer:
             self.parentData.instrumentMidiNoteOffActivity(self.idKey, pitch, velocity)

engine/instrument.py

@@ -436,7 +436,7 @@ class Instrument(object):
 
         This is only for permanent sw_last, not momentary sw_up and sw_down
         """
-        if not self.currentVariantKeySwitches:
+        if not self.currentVariantKeySwitches or not self.instrumentLayer:
             return #optimisation.
 
         if not force is None: