Historical: I am trying to get a handle on when output voltage was used to protect from faulty LEDs
I found several patents from mid-late 1998:
https://patents.google.com/patent/GB2341018A
https://patents.google.com/patent/DE19841490A1/en

This patent from 1995 includes overvoltage protection for the LED circuit, but it isn't specifically there to protect the LEDs from each other:
https://patents.google.com/patent/EP0686953A1/en

This patent from 1989 also isn't intended for an array of LEDs, but it does feature a lamp that is switched off in the case of overvoltage which could be adapted to fit what you described:
https://patents.google.com/patent/US5068570A/en