Introduced common exception superclass

CloudObjects/SDK/WebAPI/OAuth2AuthServer.php

@@ -6,7 +6,7 @@
 
 namespace CloudObjects\SDK\WebAPI;
 
-use Exception;
+use CloudObjects\SDK\Exceptions\SDKException;
 use ML\JsonLD\Node;
 use GuzzleHttp\Client;
 use Webmozart\Assert\Assert,
@@ -114,7 +114,7 @@ class OAuth2AuthServer {
                 // no additional params needed
                 break;
             default:
-                throw new Exception("No flow/grant_type found.");
+                throw new SDKException("No flow/grant_type found.");
         }
 
         $grantCacheKey = sha1(json_encode($params));