A divider would make more problems. If it's high enough to qualify as a handrail, it's gonna clip handlebars and high-side the rider. Ouch.

If it's low enough to avoid handlebars, it's just an additional tripping hazard.

In other words, a no-win situation.

But an alternative would obviously be bright yellow paint and/or an LED strip. Bright lights would probably be the best solution for approaching the steps in the dark.

Too bad we live in such a litigious society we cannot utilize simple solutions for rolling wheels. Europe has about a BILLION stair ramps for rolling bikes up and down at transit hubs and in their cities. Here, that would be quickly sued out of existence.

So far no litigation has been reported

It's been nearly four years! But still I think my advice to get a grip is good advice