🐛 Fix pickup policy picked granted session issue

pkg/server/oauth_api.go

@@ -26,10 +26,9 @@ func preConnect(c *fiber.Ctx) error {
 
 	var session models.AuthSession
 	if err := database.C.Where(&models.AuthSession{
-		AccountID:   user.ID,
-		ClientID:    &client.ID,
-		LastGrantAt: nil,
-	}).First(&session).Error; err == nil {
+		AccountID: user.ID,
+		ClientID:  &client.ID,
+	}).Where("last_grant_at IS NULL").First(&session).Error; err == nil {
 		if session.ExpiredAt != nil && session.ExpiredAt.Unix() < time.Now().Unix() {
 			return c.JSON(fiber.Map{
 				"client":  client,