BrawlBox .wav ripping from BRSAR crashes

[Khangaroo]

I'm trying to rip BGM from some random Wii channels. Most of them seem to be in a BRSAR, so I try opening it with BrawlBox. However, when I attempt to export the sound as a wav, it will error with this:

Spoiler

Object reference not set to an instance of an object.
   at System.Audio.WAV.ToFile(IAudioStream source, String path, Int32 samplePosition, Int32 maxSampleCount)
   at BrawlLib.SSBB.ResourceNodes.RSARSoundNode.Export(String outPath)
   at BrawlBox.GenericWrapper.OnExport(String outPath, Int32 filterIndex)
   at BrawlBox.GenericWrapper.Export()
   at BrawlBox.GenericWrapper.ExportAction(Object sender, EventArgs e)
   at System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)
   at System.Windows.Forms.ToolStripMenuItem.OnClick(EventArgs e)
   at System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
   at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
   at System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met)
   at System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met)
   at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
   at System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.ToolStrip.WndProc(Message& m)
   at System.Windows.Forms.ToolStripDropDown.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Am I missing something?