Creating new branch in empty repository fails silently

When you try to create a new branch in an empty repository, the action fails silently.

Steps to reproduce:

• Create new/empty repository
• Click on + button -> New branch
• Page reloads with no feedback
• (Server logs also don't show any useful information)

It's a minor thing, but not very user-friendly. Button should either be grayed out on an empty repository or an error should pop up.