IMO most accidents - especially fatal accidents - happen when people aren't paying close attention to their environment: rushing down narrow stairs without hanging on to a rail, working with dangerous equipment when distracted by something else. The body and nervous system are designed to preserve us. I don't think Kim Wall would've been doing anything but watching him, and would likely have been on high physical alert in that strange environment. I don't believe those are circumstances in which a fatal accident would happen, unless, for eg, there was a sharp/heavy object that came crashing down on her head.
Will certainly be interesting to hear what the circumstances of the accident are. The overwhelming number of those 'fell down the stairs and hit her head and died' accidents, are, IMO, murders that noone else saw.
Yes, it's pretty hard to think of a situation where she could injure herself seriously. I can really only think of a battery explosion, or getting caught by some moving parts in the engine room (unlikely she would even be there). We should have Peter Madsen's story on Tuesday. Then we can see how it holds up against the overwhelming circumstantial evidence for murder.