Ensure that images exist when reading them in
Ensure that images exist when reading them in

Kitware/sprokit,linus-sherrill/sprokit,linus-sherrill/sprokit,mathstuf/sprokit,mathstuf/sprokit,mathstuf/sprokit,Kitware/sprokit,linus-sherrill/sprokit,linus-sherrill/sprokit,Kitware/sprokit,Kitware/sprokit,mathstuf/sprokit