`RollbackWithError`修正

[H1rono]

Jomon/internal/model/tx.go

Lines 8 to 14 in cc5b265

	func RollbackWithError(tx *ent.Tx, err error) error {
	if err != nil {
	_ = tx.Rollback()
	return err
	}
	return tx.Rollback()
	}

tx.Rollbackのerrorを捨てない

ref:

• https://entgo.io/docs/transactions/
• https://pkg.go.dev/fmt#Errorf