[p5.js 2.0+ Bug Report]: Should not emit FES warnings on GLSL keywords outside of p5.strands #9038

let video;
let displaceColors;

function setup() {
  createCanvas(700, 400, WEBGL);
  displaceColors = buildFilterShader(displaceColorsCallback);
  describe(
    'A video of a city crosswalk, with colors getting more offset the further from the center they are'
  );
}

function displaceColorsCallback() { 
  // everything inside this function is p5.strands code: it is javascript-like, but it is transpiled into a glsl shader. Therefore, GLSL functions/keywords including `length` should result in FES warning not to redeclare, even though they can be redeclared OUTSIDE of this p5.strands builder.
  function zoom(coord, amount) {
    return (coord - 0.5) / amount + 0.5;
  }
  filterColor.begin();
  const length = 0; // this doesn't appear to have any effect but should result in a warning
  const uv = filterColor.texCoord;
  const r = getTexture(filterColor.canvasContent, uv).r;
  const g = getTexture(filterColor.canvasContent, zoom(uv, 1.05)).g;
  const b = getTexture(filterColor.canvasContent, zoom(uv, 1.1)).b;
  const a = getTexture(filterColor.canvasContent, uv).a;
  filterColor.set([r, g, b, a]);
  filterColor.end();
}

function draw() {
  background(255);

  circle(mouseX-width/2, mouseY-height/2, 200)
  filter(displaceColors);
}