In a situation involving a genuine error then it’s OK. A comical example is the dreaded Gazebo. Essentially if something bad happens because of something the player misunderstands but the character wouldn’t have then it’s OK.
“I attack the ancient dragon”
SPLAT.
“Whoa, WTF?! Doesn’t “ancient” mean it’s like nearly dead from old age and really infirm”
“No it means its super powerful”.
“Ohhh, sorry guys”.
Anything involving PvP I will hard nerf (unless playing a system like Paranoia or Shadowrun where that stuff is expected). Letting PvP go unchecked is a recipe for a total party meltdown and destruction of real life relationships 3 or 4 sessions later.
Other than that I will let the chips fall where they may. If the players paint themselves into a corner then I’ll install a side door for them to get out and back adventuring. If they make some bad decisions and get TPKed, well next week we start a new campaign.