Updated to show error message to all Env.

Author: vinogcs

lib/internal/Magento/Framework/Serialize/Serializer/Json.php

@@ -23,11 +23,7 @@ public function serialize($data)
     {
         $result = json_encode($data);
         if (false === $result) {
-            $errorMessage = "Unable to serialize value.";
-            if(!$this->isOnProduction()){
-                $errorMessage .= "Error: " . json_last_error_msg();
-            }
-            throw new \InvalidArgumentException($errorMessage);
+            throw new \InvalidArgumentException("Unable to serialize value. Error: " . json_last_error_msg());
         }
         return $result;
     }
@@ -40,18 +36,8 @@ public function unserialize($string)
     {
         $result = json_decode($string, true);
         if (json_last_error() !== JSON_ERROR_NONE) {
-            $errorMessage = "Unable to unserialize value.";
-            if(!$this->isOnProduction()){
-                $errorMessage .= "Error: " . json_last_error_msg();
-            }
-            throw new \InvalidArgumentException($errorMessage);
+            throw new \InvalidArgumentException("Unable to unserialize value. Error: " . json_last_error_msg());
         }
         return $result;
-    }
-    
-    private function isOnProduction(){
-        $appState = \Magento\Framework\App\ObjectManager::getInstance()
-            ->get('Magento\Framework\App\State');
-        return $appState === \Magento\Framework\App\State::MODE_PRODUCTION;
-    }
+    }    
 }