Previews don't work for unpublished pages

[thibaudcolas]

https://guide.wagtail.org/admin/pages/213/view_draft/

If a page has never been published, we can’t use the live preview, nor view_draft.

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Perhaps related to wagtail-localise field replacement not happening for drafts

[laymonage]

This is probably because of the following code

guide/apps/core/models/content.py

Lines 47 to 55 in 195797c

	def get_context(self, request, *args, **kwargs):
	if self.live and self.show_in_menus:
	context = super().get_context(request, *args, **kwargs)
	pages = Page.objects.live().in_menu()
	context.update(
	previous=pages.filter(path__lt=self.path).last(),
	next=pages.filter(path__gt=self.path).first(),
	)
	return context

It doesn't return the context at all if the page is not live. It should be changed to something like

def get_context(self, request, *args, **kwargs): 
    context = super().get_context(request, *args, **kwargs) 
    if self.live and self.show_in_menus: 
        pages = Page.objects.live().in_menu() 
        context.update( 
            previous=pages.filter(path__lt=self.path).last(), 
            next=pages.filter(path__gt=self.path).first(), 
        ) 
    return context