SPLIT xml in mutiple rows for RAISERROR insert trigger

The following code in my insert trigger returns the values all in a single row . If users are entering 1-10 rows at a time then that is fine but if they are entering 100s then the raiserror output becomes too long to read . What is the best solution for this please ?

TRIGGER CODE :

 DECLARE @level_name nvarchar(MAX) =
            (
            SELECT concat ([S_ID],'-', [l_NAME], '-')
             + '  '
            FROM inserted ic 
            where not EXISTS (SELECT 1 FROM [dbo].[LEVELS] c 
                  WHERE ic.[geo]=c.[GEO] and c.level_name=ic.[l_NAME] 
                            )
            FOR XML PATH('')
             );

        IF @level_name IS NOT NULL
            BEGIN
                RAISERROR('level name not found: %s', 16, 1, @level_name) with log;
            END;

OUTPUT :

100-A2001 101-A2001 102-A2001 .......