Fixing this is tricky. If someone can think of a better solution, please let me know.
When editing a category, both the topic templates editor and the insert hyperlink component are modals. Since we define modals using the singleton pattern, we destroy the modal containing the editor when a user wants to add a hyperlink and discard all their unsaved changes.
This PR adds a new action to the application route, which will receive a category object and open the edit modal showing the topic template tab. We pass this action as a callback to the insert-hyperlink component, to get the latest topic template with the new hyperlink.
We should later refactor this code and avoid using a modal to edit a category.