Villagers sliding off beds

Villagers sliding off beds

I was busy making an Iron Golem farm but realised that sometimes the villagers fall out of their capsules. long story short, there's a bed at the capsules for the villager to sleep. I Realised that when the villagers sleep they slide off their beds occasionally. This seems like a semi important problem because it breaks Iron farms.

I would appreciate it if y'all can look into this problem