Application on index page will not load, if something in 'site.db' is wrong

**Describe the bug**
After setup or if you create a new database file (site.db), the application won't work.

**To Reproduce**
Steps to reproduce the behavior:
1. Setup project or regenerate site.db file
2. Run application
3. Open website and see the error

**Expected behavior**
Index page should display without any checked websites

**Additional context**
The solution to this problem is already known.
The main route queries trough the database without checking if there is something in the database.
A simple check for the case of an empty table would solve this problem.