seeder中获取output失败。

[augushong]

在tp8中，通过getOutput获取输出对象失败，在之前的版本可以正常获取到。

  [TypeError]
  Phinx\Seed\AbstractSeed::getOutput(): Return value must be of type think\console\Output, null returned



Exception trace:
 () at C:\www\user_hub\vendor\topthink\think-migration\phinx\Seed\AbstractSeed.php:138
 Phinx\Seed\AbstractSeed->getOutput() at C:\www\user_hub\database\seeds\InitBaseAdminData.php:20
 InitBaseAdminData->run() at C:\www\user_hub\vendor\topthink\think-migration\src\command\seed\Run.php:96
 think\migration\command\seed\Run->executeSeed() at C:\www\user_hub\vendor\topthink\think-migration\src\command\seed\Run.php:67
 think\migration\command\seed\Run->seed() at C:\www\user_hub\vendor\topthink\think-migration\src\command\seed\Run.php:52
 think\migration\command\seed\Run->execute() at C:\www\user_hub\vendor\topthink\framework\src\think\console\Command.php:210
 think\console\Command->run() at C:\www\user_hub\vendor\topthink\framework\src\think\Console.php:649
 think\Console->doRunCommand() at C:\www\user_hub\vendor\topthink\framework\src\think\Console.php:308
 think\Console->doRun() at C:\www\user_hub\vendor\topthink\framework\src\think\Console.php:245
 think\Console->run() at C:\www\user_hub\think:12