Don't depend or specific data

We are catching all exceptions here,
but we are depending on self.project and self.version
be correctly returned from the api.
This doesn't always happens, and it's raising another error.

Author: stsewd

readthedocs/projects/tasks.py

@@ -390,8 +390,8 @@ def run(
                     'stack': True,
                     'tags': {
                         'build': build_pk,
-                        'project': self.project.slug,
-                        'version': self.version.slug,
+                        'project': self.project.slug if self.project else None,
+                        'version': self.version.slug if self.version else None,
                     },
                 },
             )