         let indexStructureParentIdx = "CREATE INDEX IF NOT EXISTS \(IndexBookmarksMirrorStructureParentIdx) " +
             "ON \(TableBookmarksMirrorStructure) (parent, idx)"
 
-        let queries: [String?] = [
+        let queries: [String] = [
             getDomainsTableCreationString(),
             getHistoryTableCreationString(),
             favicons,


        log.debug("Creating \(queries.count) tables, views, and indices.")

        return self.runValidQueries(db, queries: queries) &&
               self.prepopulateRootFolders(db)
    }


        }

        if from < 5 && to >= 5  {
            if !self.run(db, sql: getQueueTableCreationString()) {
                return false
            }
        }
