Do you want to show a table with the count of error messages for each type like below?
Using slicer will show only one errormessage for all tables, so you should not use slicer for your question. [like below]
To show dates of each error in different table, follow below steps:
1.Select table visualization, click on Errormessage and startdate and make the table twice( by ctrl+c & ctrl+v).
2. Now clcik on any one of the table, thrn go to visual filters -> Error message -> Select anyone of the message type.
repeat the same with the other table, then you can see dates for different error messages in separate tables.
Hope it helps!. Any queries do revert back.