PCB arc tracking

I've seen failures like this at 24V, where the PCB didn't draw any
more current while on fire, than it did operating normally.

Here's an article that shows ignition of a PCB from a 2032 coin cell!
http://www.kodiakconsulting.com/page19/assets/Low%20Voltage_The%20Incompetent%20Ignition%20Source_Final.pdf

I would be very interested in any pointers on how to prevent this arc
tracking on the PCB, given that preventing the initiating component
failure isn't possible/practical.

Thoughts?
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