1. Instead, use `@page.title`, since it's always guaranteed to be around
in a wiki.
2. `params[:id]` is _not_ always guaranteed to be around - if a page is
created with errors, `render :edit` is called, and `params[:id]` is
`nil`.
3. More context: https://gitlab.com/gitlab-org/gitlab-ce/issues/20079#note_13223240
