When designing a system and coming across an edge case, what do you do?

One option is to add extra complexity to the solution.

To absorb the edge case and make it fit.

This is an approach that engineering-led companies that are resource rich can do.

The complexity of the overall solution can balloon significantly with each edge case incorporated.

This is due to the pareto principle: 20% of use cases will add 80% of the cost.

Another option: what can you remove to make it so that edge case doesn't cause much harm in practice?

Cut back to the 20% cost solution that covers 80% of the value.

Subtraction is impossible to do by consensus.

Subtraction must be done by an authorial voice.