Check that the input contains a preset attribute before checking if dirty
Check that the input contains a preset attribute before checking if dirty

Fixes issues where encodes were being deleted when the parent model was updated during AJAX stuff like visiblilty toggle or drag and drop

https://bkwld.codebasehq.com/projects/bkwld/tickets/851

BKWLD/decoy,BKWLD/decoy,SomosAMambo/decoy,BKWLD/decoy,SomosAMambo/decoy,SomosAMambo/decoy