fabcar-blockchain-sample Getting error while executing registerUser.js(Need help in priority)

I am using the IBM Blockchain platform console to create the network and using the fabcar sample to connect to the network with SDK. The enrollAdmin.js script is successful but the registerUser.js is giving the below error message.

Failed to register user user1: TypeError [ERR_INVALID_ARG_TYPE]: The "options.ca" property must be one of type string, Buffer, TypedArray, or DataView. Received type object.

As per my analysis the issue is with the line. const secret = await ca.register({ affiliation: '', enrollmentID: userName, role: 'client' }, adminIdentity);

I am not sure how to resolve it,could you please help on this.