title: error TS2678 Type "'String'" is not comparable to type '""' in angular 5
body: <p>Here's my code in angular 5:</p>
  
  <pre><code>gotToWallet(wallet) {
  
    const { countryId = '', currencyType = '' } = wallet || {};
  
    let walletIdentity;
  
    switch (currencyType) {
      case 'CRYPTO':
        walletIdentity = 'userWalletIdentity';
       break;
      case 'FIAT':
        walletIdentity = 'fiatWalletIdentity';
       break;
      case 'ERC20TOKEN':
        walletIdentity = 'xbxUserWalletIdentity';
       break;
   }
  
    const { currencyId = '' } = (wallet || {})[walletIdentity] || {};
    this.router.navigate([`walletMgmt/wallet-details/${currencyId}/${countryId}`]);
  
  }
  </code></pre>
  
  <p>I am getting the following error when running <code>ng build</code> command:</p>
  
  <pre><code>ERROR in src/app/wallet-management/wallets/wallets.component.ts(202,12): error TS2678: Type '"CRYPTO"' is not comparable to type '""'.
  src/app/wallet-management/wallets/wallets.component.ts(205,12): error TS2678: Type '"FIAT"' is not comparable to type '""'.
  src/app/wallet-management/wallets/wallets.component.ts(208,12): error TS2678: Type '"ERC20TOKEN"' is not comparable to type '""'.
  </code></pre>
  
  <p>Why am i getting this error? the code seems to work fine when i run <code>ng serve</code>.
  I am getting this error only when trying to make build.</p>
  
  <p>Thanks, any help would be highly appreciated.</p>