I will bet you that your problem is in fact Photos app not the camera app.
If you’ve got a folder that has a problem like for example the date is wrong, or there are sometimes photos that are corrupted then Photos app can cause crashes.
Also if you have a jail broken iPhone it can cause problems with Photos app.
I don’t have a free Camera app for you I have never had the need for one but I would look at Photos app to see if there’s a problem there.