It appears that the official chrome webstore extension by Rob W is outdated. It was last updated in 2019. 

const defines = builder.merge(DEFINES, { GENERIC: true, TESTING: true });
  const cssDir = BUILD_DIR + "dev-css/";
  return merge([
    gulp.src("web/images/*", { base: "web/" }).pipe(gulp.dest(cssDir)),
    preprocessCSS("web/viewer.css", defines)
      .pipe(
        postcss([
          postcssLogical({ preserve: true }),
          postcssDirPseudoClass(),
          autoprefixer({ overrideBrowserslist: ["last 1 versions"] }),
        ])
      )
      .pipe(gulp.dest(cssDir)),
  ]);
});
gulp.task(
  "dev-sandbox",
  gulp.series(
    function scriptingDevSandbox() {
      const defines = builder.merge(DEFINES, { GENERIC: true, TESTING: true });
      return createTemporaryScriptingBundle(defines, {
        disableVersionInfo: true,
      });
    },
    function createDevSandbox() {
      console.log();
      console.log("### Building development sandbox");
      const defines = builder.merge(DEFINES, { GENERIC: true, TESTING: true });
      const sandboxDir = BUILD_DIR + "dev-sandbox/";
      rimraf.sync(sandboxDir);