diff --git a/composer.json b/composer.json
index fdd491a..b4789ed 100644
--- a/composer.json
+++ b/composer.json
@@ -35,7 +35,10 @@
         }
     },
     "config": {
-        "sort-packages": true
+        "sort-packages": true,
+        "allow-plugins": {
+            "ergebnis/composer-normalize": true
+        }
     },
     "extra": {
         "branch-alias": {
diff --git a/src/Client.php b/src/Client.php
index 92c0afb..1951533 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -70,12 +70,12 @@ public function __call($name, $arguments)
                 throw new RecvFailedException('Recv failed');
             }
 
-            return with($packer->unpack($ret), function ($data) {
+            return with((array) $packer->unpack($ret), function ($data) use ($ret) {
                 if (array_key_exists('result', $data)) {
                     return $data['result'];
                 }
 
-                throw new ServerException($data['error'] ?? []);
+                throw new ServerException($data['error'] ?? ['code' => 0, 'message' => 'Invalid data: ' . $ret]);
             });
         };