No, we don't want it to implicitly be a list item. We want it to fail as invalid syntax. If I wanted the two and three strings to be combined, I would have /exp

No, we don't want it to implicitly be a list item. We want it to fail as invalid syntax. If I wanted the two and three strings to be combined, I would have /explicitly/ used an operator for that. It's the implicit behavior of that which is the problem.