I am not sure what happened, but for some reason I have the Birdhouse, but also it is still in the options to buy with red text. But my egg also won't be destroyed/Cracked, and I believe it is due to the birdhouse not being registrated as build.
(My second play through)
A similar bug where when playing again without refreshing the browser would result in the first egg not breaking was reported a while ago. This may be ur case.
I will deploy a fix for this with the next patch.
As a temporary solution, you can refresh the browser and start a new game.
Sorry you had to experience this and thank you for the report !