What if a landlord illegally enters your apartment to find something you're doing which violates the terms of your lease?

I know this may be more easily answerable in r/legaladvice, but this is hypothetical so not sure if it belongs there.

Suppose an apartment contract (lease agreement) says you can't (for example) have pets, and if you ever have a pet in your apartment, you are in violation of your lease agreement.

What happens if the landlord illegally enters your apartment and then finds that you have a pet in your apartment, and claims you broke the lease? Who is "favored" legally speaking? The tenant, because the landlord first illegally entered the apartment before finding out about the pet? Or the landlord, because the tenant was still violating the terms of the lease?

Edit: By "illegally enters," I mean for example if the landlord decides to enter one day without prior notice and without having any emergency, and without satisfying any of the other predicates necessary for allowing a landlord to enter an apartment.