[airbreather]

Maybe you are worried about not how it will work, but the myriad of ways it might fail under unusual/unexpected circumstances?

I particularly feel this anxiety when writing code for real time safety/automation/process control systems of plant and machinery.

For me this is as the consequences can be quite visible and quite expensive - many tonnes of equipment or megawatts of power may be involved and you can't just reboot it to fix it once the equipment is damaged. Also a lot of peoples jobs may be impacted, so others are relying heavily on you to get it right.

I find that good architecture/data structures go a long way to allowing a feeling of ease as these enable simpler code to be created. That and use of state machines so the behaviors are exhaustively and unambiguously defined and if well structured then debugging is limited to small parts of the code related to a particular state or transition.