What object type to pass to seriously.js seriously.source() when using React 16 and Agora 4.18 SDK for web

Question

I'm getting this error no matter what type of object I pass when calling seriously.source(myobject):

> seriously.js:3331 Uncaught Error: Unknown source type
    at new SourceNode (seriously.js:3331:1)
    at findInputNode (seriously.js:1623:1)
    at Seriously.source (seriously.js:4833:1)
    at eval (HostView.jsx:127:1)

I checked the seriously docs on github in their wiki, and I see examples, but no spec as to what type is required.

I'm trying to apply various effects (like chromakey) by drawing the camera input to a canvas, applying the effects, then passing the canvas as the MediaTrack to the output (into an Agora video conference).

I've tried passing a MediaStreamTrack, a MediaStream. When I create the MediaStream by calling like this:

navigator.mediaDevices.getUserMedia(mediaObject)
    .then((mediaStream) => {

      streamingToCanvas = true;

      const videoSource = mediaStream.getVideoTracks()[0];
      const audioSource = mediaStream.getAudioTracks()[0];
      const canvas = intermediateCanvasRef.current;
      const ctx = canvas.getContext("2d");

      let canvasStream;
      video = intermediateVideoRef.current;
      video.srcObject = mediaStream;
      setCameraStream(mediaStream);

Here is the relevant seriously.js code:

 let seriously = new Seriously();
  let huesat = seriously.effect('hue-saturation');
  let bricon = seriously.effect('brightness-contrast');
  let chroma = seriously.effect('chroma');
  let blend = seriously.effect('blend');
  let transform = seriously.transform('reformat');
  let intermediateCanvasRef = useRef();
  let intermediateVideoRef = useRef();
  let source;
  let target;
  let strack;
  let sstream;

  chroma.weight = chromaWeight;
  chroma.balance = chromaBalance;
  chroma.clipWhite = chromaClipWhite;
  chroma.clipBlack = chromaClipBlack;
  chroma.mash = chromaMask;
  chroma.screen = chromaScreen;

  useEffect(()=>
  {
    if(!channelParameters || !channelParameters.localVideoTrack)
      return;
    strack = channelParameters.localVideoTrack;
    sstream = video.srcObject;
    source = seriously.source(sstream);
    console.log("SOURCE", source);
    target = seriously.target(intermediateCanvasRef.current);

    if(chromakeying)