How to return NDVI as UINT 16 in an Evalscript

ndvi_unit16.js

//VERSION=3
function setup() {
  return {
    input: ["B04", "B08"],
    output: { bands: 1, sampleType: "UINT16" }
  };
}

function evaluatePixel(sample) {
let ndvi = index(sample.B08, sample.B04);
return [10000 * ndvi + 10000];
}