add return value to 'PostProcessor._init_archive()'

gallery_dl/postprocessor/common.py

@@ -45,5 +45,7 @@ class PostProcessor():
                     self.name, archive, exc.__class__.__name__, exc)
             else:
                 self.log.debug("Using %s archive '%s'", self.name, archive)
+                return True
         else:
             self.archive = None
+        return False

gallery_dl/postprocessor/python.py

@@ -22,8 +22,7 @@ class PythonPP(PostProcessor):
         module = util.import_file(module_name)
         self.function = getattr(module, function_name)
 
-        self._init_archive(job, options)
-        if self.archive:
+        if self._init_archive(job, options):
             self.run = self.run_archive
 
         events = options.get("event")