fix：null警告

ZR.Admin.WebApi/Controllers/System/CodeGeneratorController.cs

@@ -256,7 +256,7 @@ namespace ZR.Admin.WebApi.Controllers
         [ActionPermissionFilter(Permission = "tool:gen:code")]
         public IActionResult CodeGenerate([FromBody] GenerateDto dto)
         {
-            if (dto?.TableId <= 0)
+            if (dto == null || dto.TableId <= 0)
             {
                 throw new CustomException(ResultCode.CUSTOM_ERROR, "请求参数为空");
             }

ZR.Admin.WebApi/Controllers/System/TasksController.cs

@@ -70,7 +70,7 @@ namespace ZR.Admin.WebApi.Controllers
             {
                 return SUCCESS(_tasksQzService.GetId(id));
             }
-            return SUCCESS(null);
+            return SUCCESS(0);
         }
 
         /// <summary>