Return type of exported function has or is using name 'IMemoized' from external module "lru-memoizer" but cannot be named

[aschekatihin]

Error in new Typescript 3.4:

clwy-node-jwks-rsa/wrappers/cache.ts(7,17): error TS4058: Return type of exported function has or is using name 'IMemoized' from external module "lru-memoizer" but cannot be named.

Example (from clwy-node-jwks-rsa):

export function cacheSigningKey(client: JwksClient, cacheMaxEntries: number = 5, options = {cacheMaxAge: ms('10h') }) {
  const logger = debug('jwks');
  const getSigningKey = client.getSigningKey.bind(client);

  logger(`Configured caching of singing keys. Max: ${cacheMaxEntries} / Age: ${options.cacheMaxAge}`);

  return memoizer({
    load: (kid, callback) => {
      getSigningKey(kid, (err, key) => {
        if (err) {
          return callback(err);
        }

        logger(`Caching signing key for '${kid}':`, key);
        return callback(null, key);
      });
    },
    hash: kid => kid,
    maxAge: options.cacheMaxAge,
    max: cacheMaxEntries
  });
}

As interfaces aren't really exported in typings - typescript guesses return type correctly as IMemoized here but cannot really use it.

So, as temporary fix

export function cacheSigningKey(client: JwksClient, cacheMaxEntries: number = 5, options = {cacheMaxAge: ms('10h') }): any {

works, but type info is obviously lost