Removed the "all files are refs" error message and made the "no files, can't scan" message quicker. That's because when scanning iPhoto libraries with big libraries, the GUI would hang because these checks would involve loading the whole library.

core/app.py

@@ -33,9 +33,6 @@ JOB_DELETE = 'job_delete'
 class NoScannableFileError(Exception):
     pass
 
-class AllFilesAreRefError(Exception):
-    pass
-
 class DupeGuru(RegistrableApplication, Broadcaster):
     DEMO_LIMIT_DESC = "In the demo version, only 10 duplicates per session can be sent to the recycle bin, moved or copied."
     
@@ -347,12 +344,8 @@ class DupeGuru(RegistrableApplication, Broadcaster):
             logging.info('Scanning %d files' % len(files))
             self.results.groups = self.scanner.GetDupeGroups(files, j)
         
-        files = self.directories.get_files()
-        first_file = first(files)
-        if first_file is None:
+        if not self.directories.has_any_file():
             raise NoScannableFileError()
-        if first_file.is_ref and all(f.is_ref for f in files):
-            raise AllFilesAreRefError()
         self.results.groups = []
         self._start_job(JOB_SCAN, do)