According to both crash logs, Photos is crashing at the same code in both logs, when trying to access the character in a string. It looks like a data error. Does the name string of your dog contain special characters? Or could one of the image files in the people album of your dog have a problematic filename? For example non-printable characters?
Can you work with photos of your dog, that you tried to use as the key photo? Add adjustments to the photos? Can you export the unmodified original and the adjusted version?
In addition to the tests already recommended by Richard I would also test with a new, empty Photos Library, import a few photos of your dog, then test in this library.