In this case I would go back to the beginning and start over; meaning I would put the old screen back in (assuming it's still functional, just cracked) and see if the problem is still there.
If everything works with the original screen, then there's something going on with the replacement screen that's affecting your camera, as odd as that would be.
If the problem is still present, though, that would indicate that something went wrong with your repair, sorry to say.
We just solved a similar problem on an iPhone here the other day; the new screen had a cover over the camera's peephole that was supposed to be removed when the screen was installed. Because the user hadn't removed it, all they saw was a black screen. That doesn't sound like your situation due to the error message you're getting, but it might be worth checking; maybe the camera is smart enough to know that it shouldn't be seeing a full black screen.
Just to clarify; which camera do you believe is giving you the error? Is it possible to switch between the front and rear camera? Which one comes up by default when you bring up your camera app?
But yeah, if it was me I'd try swapping the original screen back in to figure out where the problem is coming from.
Let us know what you find.