fix invalid key cause validate_file_format throws exception
fix invalid key cause validate_file_format throws exception

sometimes user may use such url: https://unsplash.it/375/333 and it will cause exception.

owen2345/camaleon-cms,owen2345/camaleon-cms,SecondBureau/camaleon-cms,owen2345/camaleon-cms,beansmile/camaleon-cms,SecondBureau/camaleon-cms,beansmile/camaleon-cms,SecondBureau/camaleon-cms,pulkit21/camaleon-cms,beansmile/camaleon-cms,brian-kephart/camaleon-cms,durchdiestadt/camaleon-cms,durchdiestadt/camaleon-cms,pulkit21/camaleon-cms,brian-kephart/camaleon-cms,durchdiestadt/camaleon-cms,pulkit21/camaleon-cms,brian-kephart/camaleon-cms