Blue loading screen error

So i’m trying to hide a part on my scene on AFrame by using a-entity for the beging below a-scene and another one simular to that at the bottem of the index above a-scene but before I can type false to cover the part of the scene and make it blank the room shows a Blue loading screen and does not work… it works fine when i take off a-entity.So what am I doing wrong to get a Blue error screen instead of a blank cover up screen , or how can I cover up a part of the scene to make the room blank?(I do not mean deleting the code)sorry if it sounds like im speaking gibberish im new to this site