fix

api/controllers/IssueChainController.php

@@ -39,7 +39,7 @@ class IssueChainController extends BaseController
         foreach ($chain_model as &$val) {
             $val->chain_name = isset($val->chain->platform) ? $val->chain->platform : '';
             $val->issue_charge = (int)$val->issue_charge;
-            $val->charge_unit = $val->gas->coin_name;
+            $val->charge_unit = isset($val->gas->coin_name) ? $val->gas->coin_name : '';
             unset($val->download_url);
             unset($val->introduce);
             unset($val->create_time);