Describe the bug
When I go to a Conference, and it has Partners without a link, in the frontend is linking to the same page of the Conference

To Reproduce
Steps to reproduce the behavior:

1. As admin, configure a Conference with a Partner without a Link
2. Go to the Conference, find the Partner
3. Click in the logo
4. See that you're in the same page

Expected behavior
To not have any link if it isn't configured

Screenshots

Extra data (please complete the following information):

• Decidim Version: 0.28.0.dev
• Decidim installation: Alpha Try Decidim

Additional context

It's the same for Organizations