update

app/Transformers/FeedTransformer.php

@@ -33,7 +33,7 @@ class FeedTransformer extends TransformerAbstract {
             'type' => $feed['type'],
             'relate_id' => $feed['relate_id'],
             'relate_data' => $feed['relate_data'],
-            'content' => json_decode($feed['content']),
+            'content' => !empty($feed['content'])?json_decode($feed['content']):'',
             'created_at' => Carbon::parse($feed['created_at'])->diffForHumans(),
         ];
     }