Fixed issue with empty response stream in Yii2 (#5180)

Author: SamMousa

src/Codeception/Lib/Connector/Yii2.php

@@ -341,7 +341,7 @@ public function doRequest($request)
         }
 
         $content = ob_get_clean();
-        if (empty($content) && !empty($response->content)) {
+        if (empty($content) && !empty($response->content) && !isset($response->stream)) {
             throw new \Exception('No content was sent from Yii application');
         }