Blocs crashes when I try to open a project


I last edited a project last month and all was fine; it was just some small text copy edits. I go to open today and blocs keeps unexpectedly quitting.

Apple problem report says:

“Application Specific Information:
*** Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘-[NSNull customURL]: unrecognized selector sent to instance 0x7fff878ff020’
abort() called
terminating with uncaught exception of type NSException”

Other files open fine. Previously never had an issue with the project I’m currently trying to open. Working with version 4.5.3. Thanks!