[sellyme]

> Puzzles in commercial collections don't usually have that problem,

I would argue that puzzles in commercial collections are more likely to have that problem than ones made freely available by hobbyists, as commercial enterprises inevitably cut corners on things like labour costs for an actual human setter.

I have seen dozens of commercial puzzle games and applications that do not make any attempt to verify the (auto-generated) puzzles as solvable, but I don't think I've ever had the same problem on a site like LMD.