Prototypes. When you have a design element in mind, you prototype it. This may mean writing multiple programs before producing the final program(s). Using the same language for your prototypes as for your final (target) system mitigates the concern there because you can take components of your prototypes and turn them into modules/libraries used by the final system.

Testing. Always test the system. Automate every test you can so you can trigger them and get a report once completed rather than wasting your time clicking buttons or typing in commands.