BufferingAudioReader: Clear buffer in timeout unit test

modules/juce_audio_formats/format/juce_BufferingAudioFormatReader.cpp

@@ -276,6 +276,8 @@ public:
             bufferingReader.setReadTimeout (10);
 
             AudioBuffer<float> readBuffer { 2, 1024 };
+
+            readBuffer.clear();
             read (bufferingReader, readBuffer);
 
             expect (isSilent (readBuffer));