Added a workaround to avoid a crash in broken JUCE 4.1 synth plug-ins

modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp

@@ -1598,8 +1598,9 @@ private:
 
         HeapBlock<VstSpeakerConfiguration> inArrBlock (1, true), outArrBlock (1, true);
 
-        VstSpeakerConfiguration* inArr = inArrBlock.getData(), *outArr = outArrBlock.getData();
-        if (effect->dispatchFunction (effect, plugInOpcodeGetSpeakerArrangement, 0, reinterpret_cast<pointer_sized_int> (&inArr), &outArr, 0.0f) == 0)
+       VstSpeakerConfiguration* inArr = inArrBlock.getData(), *outArr = outArrBlock.getData();
+        if (effect->numInputChannels == 0 ||
+            effect->dispatchFunction (effect, plugInOpcodeGetSpeakerArrangement, 0, reinterpret_cast<pointer_sized_int> (&inArr), &outArr, 0.0f) == 0)
             inArr = outArr = nullptr;
 
         for (int dir = 0; dir < 2; ++dir)