auhal: fail in render callbacks if bytesToCopy is <= 0

This should not happen in the current implementation.

modules/audio_output/auhal.c

@@ -1446,13 +1446,12 @@ static OSStatus RenderCallbackAnalog(vlc_object_t *p_obj,
         memset(targetBuffer, 0, bytesRequested);
     } else {
         int32_t bytesToCopy = __MIN(bytesRequested, availableBytes);
+        assert(bytesToCopy > 0);
 
-        if (likely(bytesToCopy > 0)) {
         memcpy(targetBuffer, buffer, bytesToCopy);
         TPCircularBufferConsume(&p_sys->circular_buffer, bytesToCopy);
         ioData->mBuffers[0].mDataByteSize = bytesToCopy;
     }
-    }
 
     vlc_cond_signal(&p_sys->cond);
     vlc_mutex_unlock(&p_sys->lock);
@@ -1494,6 +1493,7 @@ static OSStatus RenderCallbackSPDIF(AudioDeviceID inDevice,
         memset(targetBuffer, 0, bytesRequested);
     } else {
         int32_t bytesToCopy = __MIN(bytesRequested, availableBytes);
+        assert(bytesToCopy > 0);
 
         memcpy(targetBuffer, buffer, bytesToCopy);
         TPCircularBufferConsume(&p_sys->circular_buffer, bytesToCopy);