Ask HN: Should coders usually offer a warranty for bug-free software?

Usually? No.

Unless you're compensated multiple times what a no-warranty version would cost, and do it for an industry where bug-free matters. And even then that's a question for the company lawyers as well. In short: if you ask on HN, it's almost certain you shouldn't try.

What you may be interested in is some form of a license / retainer, where you're available to the company as a contractor for X amount of time to fix potential issues raised. But don't ever mention bug-free and rent out your time, not results.

Contractually, you can make whatever agreements you want. I would consider someone offering a warrantee for bug free software to be an inexperienced amateur. I would consider someone expecting a warrantee for bug free software an unrealistic and thus bad client.

Now obviously, if you are making software for a medical device and you are willing to pay for what that entails, you can get very close to “probably won’t kill someone” but it still probably won’t be bug free.

I would consider also "No". If you i would consider to offer a "bug free" version i would charge a lot more for it and i would include a description of what is a bug and what is not considered a bug. Also i would include a description under which circumstances the software should be run (like hardware, software). If the customer updates host OS or changes platform/browser i can't warrant bug free behavior.