For reference:
https://github.com/mozilla/pdf.js/issues/15571#issuecomment-1278141781
static _colorsMapping = new Map([
    ["CanvasText", [0, 0, 0]],
    ["Canvas", [255, 255, 255]],
  ]);
  get _colors() {
    if (
      typeof PDFJSDev !== "undefined" &&
      PDFJSDev.test("LIB") &&
      typeof document === "undefined"
    ) {
      return shadow(this, "_colors", ColorManager._colorsMapping);
    }
    const colors = new Map([
      ["CanvasText", null],
      ["Canvas", null],
    ]);
    getColorValues(colors);
    return shadow(this, "_colors", colors);
  }
  /**
   * In High Contrast Mode, the color on the screen is not always the
   * real color used in the pdf.
   * For example in some cases white can appear to be black but when saving
   * we want to have white.
   * @param {string} color
   * @returns {Array<number>}
   */
  convert(color) {