Most WaaS-specific methods require you to pass a WaaS WalletAccount object. If you want to check if a certain wallet account is a WaaS WalletAccount, you can use the isWaasWalletAccount helper method to avoid type errors. 
import { isWaasWalletAccount } from '@dynamic-labs-sdk/client/waas';

const someAction = async (walletAccount) => {
  if (!isWaasWalletAccount(walletAccount)) {
    throw new Error('This wallet account is not a WaaS wallet account');
  }

  // Do something with WaaS, like export a private key
  // ...
}