fix empty date issue if the alias has legacy empty data, code refact.

djangocms_version_locking/monkeypatch/djangocms_alias/admin.py

@@ -36,10 +36,11 @@ def _get_content_obj(self, obj: Alias):
         return content_obj
 
     def _get_edit_link(self, obj: Alias, request: HttpRequest, disabled: bool = False):
-        if self._get_content_obj(obj):
+        obj_content = self._get_content_obj(obj)
+        if not obj_content:
             # Don't display the link if it can't be edited, as the content is empty.
             return ""
-        version = proxy_model(self._get_content_obj(obj).versions.all()[0], self._get_content_obj(obj))
+        version = proxy_model(obj_content.versions.all()[0], obj_content)
 
         if version.state not in (DRAFT, PUBLISHED):
             # Don't display the link if it can't be edited
@@ -73,10 +74,11 @@ def _get_edit_link(self, obj: Alias, request: HttpRequest, disabled: bool = Fals
         )
 
     def _get_manage_versions_link(self, obj: Alias, request: HttpRequest, disabled: bool = False):
-        if self._get_content_obj(obj):
+        obj_content = self._get_content_obj(obj)
+        if not obj_content:
             # Don't display the link if it can't find version list urls, as the content is empty.
             return ""
-        url = version_list_url(self._get_content_obj(obj))
+        url = version_list_url(obj_content)
         return self.admin_action_button(
             url,
             icon="list-ol",