An unspecified error occurred. Please contact us for assistance Magento 2

Appearing after modifying vendor\magento\module-customer\Controller\Account\LoginPost.php to make it show more details by adding this code:

$message = $e->getMessage();
$this->messageManager->addError($message);

before

$this->messageManager->addErrorMessage(
     __('An unspecified error occurred. Please contact us for assistance.')
);