JwksClient is throwing error when called using non-hardcoded URI options

[sathyarajagopal]

The below code works
const clientAlt = jwksClient({
jwksUri: 'https:///<jwks_endpoint>'
});
whereas the below doesn't
const client = jwksClient({
jwksUri: constants.URLS.OIDC_JWKS_URL
});

As you can see the only difference is in the second one, I am reading the URL from a constants variable instead of hardcoding it. Can you help?