query {
  tasks {
    id
    taskName
    taskStatus
    userId
  }
}

App
 ↳--TaskList (props: tasks)
    ↳--TaskListItem (props: task)

const TaskListItemContainer = createFragmentContainer(
    TaskListItem,
    graphql`
        fragment TaskListItem_task on task {
            id
            taskName
            taskDone
            authorId
        }
    `
);

const TaskListContainer = createFragmentContainer(
    TaskList,
    graphql`
        fragment TaskList_tasks on task {
            tasks {
                id
                taskName
                taskDone
                authorId
            }
        }
    `
);

<QueryRenderer
   environment={relayEnvironment}
   query={graphql`
       query AppQuery {
         ...TaskList_tasks
       }
     `
   }

Fragment "TaskList_tasks" cannot be spread here as objects of type "Query" can never be of type "task".

App.js (3:15)
2:             query AppQuery {
3:               ...TaskList_tasks
                 ^
4:             }