Is it impossible to create an internal link when no link suggestion service is available

Reproduction steps

1. Edit a page with the github backend (or any backend without a link suggestion service)
2. try to insert an internal link manually (this step can also be attempt on any backend by fully typing a page reference manually, without using the suggestions dropdown)

Expected 

The link is inserted (possibly with some element on the UI warning that the internal page is not known, but we don't support that ye).

Actual

Is is simply impossible to insert the link as pressing enter does nothing when the page is not selected from the suggestions.