Hello,
I was doing a demo of all the advantages of the Cuba platform used in Our Internal Solution,
when someone ask me about the report which i didn’t implement in our solution yet, i came up with the very good idea to show them in the Demo Library Application, that problem is: IT IS BROKEN! 
I think is important to have this working because sometimes is the first thing we developers take a loot before get into the Platform, and for my particular case: I had the bad luck to show this in a really important moment but in a very bad time
https://demo.cuba-platform.com/app/#!
Reports → Books by Authon → RUN And i GET
PSQLException: ERROR: column t1.input_entity_types_idx does not exist
Position: 40
