Add error instead of empty array

Author: barryvdh

src/DebugBar/DebugBar.php

@@ -251,7 +251,9 @@ public function getDataAsHeaders($headerName = 'phpdebugbar', $maxHeaderLength =
         )));
 
         if (strlen($data) > $maxTotalHeaderLength){
-            return array();
+            $data = rawurlencode(json_encode(array(
+                'error' => 'Maximum header size exceeded'
+            )));
         }
 
         $chunks = array();