I have several lasers in that category somewhere in the depths of the electronics stuff i accumulated from hoarding and reselling it for years, including a surplus fiber laser i auctioned myself into owning. They can certainly start fires under the right conditions, but that requires the fiber end to be polished VERY well, otherwise, the beam isn’t focused enough to deliver the needed energy, bundled up on one spot. Still way enough to make you blind before you notice tho, nothing to skimp on in any case.

Probably the power would stop when the fault is detected.