Update for feedback

Core/Blockchain/Wallets/OnChain/Balance.php

@@ -62,7 +62,7 @@ class Balance
         $balance = $this->token->balanceOf($address);
 
         if ($balance === null) {
-            throw new \Exception('Unable to retrieve balance');
+            return null;
         }
         
         $this->cache->set($cacheKey, serialize($balance), 60);

Spec/Core/Blockchain/Wallets/OnChain/BalanceSpec.php

@@ -90,6 +90,6 @@ class BalanceSpec extends ObjectBehavior
 
         $this->setUser($user);
 
-        $this->shouldThrow(new \Exception("Unable to retrieve balance"))->duringGet();
+        $this->get()->shouldReturn(null);
     }
 }