The bug

If all villagers are struck by lightning during a raid, the villagers will then become witches but the raid still continues. You can however get a raid victory with no villagers and can still achieve the "Hero of The Village" advancement and status effect.

To reproduce

1. Cause a raid in a village
2. Run the command to turn all villagers into witches

    /execute at @e[type=villager] run summon lightning_bolt 

   → The bossbar then fills up as the villagers that are now witches join and raids the village

You can however end the raid in a defeat by just destroying the all of the nearby workstations/jobsites, beds and bells in the premises.