Cannot access villager's trades when holding spawn egg

While messing with villagers in creative to see if I could get mending, I tried to access a villager's trades while I had a villager spawn egg in my hand, but I could not access the trade.

Expected Results:
I could be able to access the villager's trades.

Observed Results:
I could not access the villager's trades.

Steps to Reproduce:

1. Spawn a villager
2. Right-click on it while holding a spawn egg
3. It doesn't let you access the trades