What does "immune to errors" mean?

After leveling up the Robot, I was offered a Buster Sword as a reward. The Buster Sword's description states "Do ☐ damage, immune to errors".

What does "immune to errors" mean?

Solution 1:

Immune to errors means the Buster Sword can still be used if you roll above your target CPU while playing as the Robot.

According to the Dicey Dungeons Wiki, this works differently in Episode 3 (You Choose You Lose).

The Buster Sword's immunity to errors includes an inability to be removed in the episode "You Choose, You Lose." It can however still be targeted to be deleted, making it best to be used last so it can continue to protect your other equipment.