TypeError: unsupported operand type(s) for *: 'NoneType' and 'int' on +repository-size page

OOPS-23b453907564a28ba65935d86d3df5a1 was logged when the user tried to access the +repository-size page.

  Module zope.traversing.adapters, line 138, in traversePathElement
    return traversable.traverse(nm, further_path)
   - __traceback_info__: (<zope.browserpage.metaconfigure.SimpleViewClass from /srv/launchpad.net/production/launchpad-rev-14996/lib/lp/soyuz/browser/../templates/archive-index.pt object at 0x10300f10>, 'repository_usage')
  Module zope.traversing.adapters, line 44, in traverse
    attr = getattr(subject, name, _marker)
   - __traceback_info__: (<zope.browserpage.metaconfigure.SimpleViewClass from /srv/launchpad.net/production/launchpad-rev-14996/lib/lp/soyuz/browser/../templates/archive-index.pt object at 0x10300f10>, 'repository_usage', [])
  Module lp.services.propertycache, line 116, in __get__
    value = self.populate(instance)
  Module lp.soyuz.browser.archive, line 620, in repository_usage
    quota = self.context.authorized_size * (2 ** 20)
TypeError: unsupported operand type(s) for *: 'NoneType' and 'int'