I saw that the initialization was missing but if I have to initialize the variable with a table this is a limitation of the library.
Its like you are saying. I know I was told this vehicle does not have fuel, I will start its engine anyway, it will start. It wont.
If you read the first post of BANanoConnect, its clear that the library is built for CRUD functionality. SHOW TABLES is not a CRUD function because it does not do INSERT, SELECT, UPDATE and DELETE, so the library does not have limits for CRUD because it was built for that and nothing else.
Its an open source project, you are welcome to update the code to suit your needs or rather write your own library. So just to be emphasize for you and anyone else who wants to use it, you cannot use any class of this library without initializing it first.
In your particular case, you want to show table names with the assumption that you don't know the table names. Perhaps try this.
dbsql.Initialize("unknown", "unknown", "unknown")
Good luck
PS: As you have not uploaded any example source project to help you further with this, helping you further will be challenging.