code: function packageReqFromBundle(mId) {
    const possibleIds = nodejsIds(mId);
    const bundleName = Object.keys(_bundles).find(bn =>
      possibleIds.some(d => {
        const pack = _bundles[bn].package;
        if (pack.hasOwnProperty(d)) return true;
        const p = parse(d);
        // For module with unknown plugin prefix, try bareId.
        // This relies on dumber bundler's default behaviour, it write in bundle config
        // both 'foo.html' and 'text!foo.html'.
        if (p.prefix) return pack.hasOwnProperty(p.bareId);
      })
    );
  
    if (bundleName) {
      return loadBundle(bundleName)
      .then(() => {
        if (packageSpace.has(mId)) return packageSpace.req(mId);
        const tried = tryPlugin(mId, packageSpace);
        if (tried) return tried;
        throw new Error(`module "${mId}" is missing from bundle "${bundleName}"`);
      });
    }
  
    const err = new Error(`no bundle for module "${mId}"`);
    err.__unkown = mId;
    throw err;
  }
docs: incoming id is already mapped return a promise to load additional bundle or throw an error to help userSpaceTesseract to identify sync return.