message: Updated error messages in file map url loader to be specific about 2 cases.
diff: @@ -45,10 +45,14 @@ export class FileMapUrlLoader implements UrlLoader {
  const file = this.files.get(parseUrl(url).pathname)!;
  if (file == null) {
  - if (this.fallbackLoader && this.fallbackLoader.canLoad(url)) {
  + if (this.fallbackLoader) {
  + if (this.fallbackLoader.canLoad(url)) {
  return this.fallbackLoader.load(url);
  }
  - throw new Error(`File ${url} not present in file map.`);
  + throw new Error(
  + `${url} not present in file map and fallback loader can not load.`);
  + }
  + throw new Error(`${url} not present in file map and no fallback loader.`);
  }
  return file.contents.toString();
  