Validation check for not removing the last account admin

pkg/services/sqlstore/account_users.go

@@ -47,6 +47,20 @@ func RemoveAccountUser(cmd *m.RemoveAccountUserCommand) error {
 	return inTransaction(func(sess *xorm.Session) error {
 		var rawSql = "DELETE FROM account_user WHERE account_id=? and user_id=?"
 		_, err := sess.Exec(rawSql, cmd.AccountId, cmd.UserId)
+		if err != nil {
+			return err
+		}
+
+		// validate that there is an admin user left
+		res, err := sess.Query("SELECT 1 from account_user WHERE account_id=? and role='Admin'", cmd.AccountId)
+		if err != nil {
+			return err
+		}
+
+		if len(res) == 0 {
+			return m.ErrLastAccountAdmin
+		}
+
 		return err
 	})
 }