Really? Faulty chords are that dangerous? I have to train the mixolydic jazz scale...
Or did you mean "cords" ?

But honestly, maybe I should also check whether my general liability insurance would cover accidents that happen while being commercially active.
Presently I'm about to take out a music instrument insurance covering theft/burglary and damage, as I got to know that my home contents insurance doesn't cover items used for commercial purposes.