Controllers/api/v2/blockchain/wallet.php

@@ -50,7 +50,10 @@ class wallet implements Interfaces\Api
                 $offChainBalanceVal = BigNumber::_($offChainBalance->get());
                 $offchainAvailableVal = BigNumber::_($offChainBalance->getAvailable());
 
-                $balance = $onChainBalanceVal->add($offChainBalanceVal);
+                
+                $balance = $onChainBalanceVal
+                    ? $onChainBalanceVal->add($offChainBalanceVal)
+                    : $offChainBalanceVal;
 
                 $wireCap = Di::_()->get('Blockchain\Wallets\OffChain\Cap')
                     ->setUser(Session::getLoggedinUser())

Core/Blockchain/Wallets/OnChain/Balance.php

@@ -60,6 +60,11 @@ class Balance
         }
 
         $balance = $this->token->balanceOf($address);
+
+        if ($balance === null) {
+            return null;
+        }
+        
         $this->cache->set($cacheKey, serialize($balance), 60);
 
         return $balance;

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

@@ -70,4 +70,26 @@ class BalanceSpec extends ObjectBehavior
         $this->setUser($user);
         $this->get()->shouldReturn(0);
     }
+
+    public function it_should_not_store_null_values_in_cache(User $user)
+    {
+        $user->getEthWallet()
+            ->shouldBeCalled()
+            ->willReturn('0x123');
+
+        $this->cache->get('blockchain:balance:0x123')
+            ->shouldBeCalled()
+            ->willReturn(null);
+
+        $this->token->balanceOf('0x123')
+            ->shouldBeCalled()
+            ->willReturn(null);
+
+        $this->cache->set('blockchain:balance:0x123', null, 60)
+            ->shouldBeCalledTimes(0);
+
+        $this->setUser($user);
+
+        $this->get()->shouldReturn(null);
+    }
 }