update allocateRenderResourcesAndReturnError

VolumePluginAudioUnit.m

- (BOOL)allocateRenderResourcesAndReturnError:(NSError **)outError {
    if (![super allocateRenderResourcesAndReturnError:outError]) {
        return NO;
    }
    
    // Validate that the bus formats are compatible.
    if (self.outputBus.format.channelCount != _inputBus.format.channelCount) {
        if (outError) {
            *outError = [NSError errorWithDomain:NSOSStatusErrorDomain code:kAudioUnitErr_FailedInitialization userInfo:nil];
            NSLog(@"kAudioUnitErr_FailedInitialization at %d", __LINE__);
        }
        self.renderResourcesAllocated = NO;
        return NO;
    }
    // Allocate your resources.
    _buffer.maxFrames = self.maximumFramesToRender;
    _buffer.pcmBuffer = [[AVAudioPCMBuffer alloc] initWithPCMFormat:_inputBus.format frameCapacity: self.maximumFramesToRender];
    _buffer.originalAudioBufferList = _buffer.pcmBuffer.audioBufferList;
    _buffer.mutableAudioBufferList = _buffer.pcmBuffer.mutableAudioBufferList;
    return YES;
}