Prevent deleted/removed posts from being stickied

When a stickied post gets deleted or removed, it automatically gets
removed as a sticky. However, it's currently still possible to add
deleted/removed posts as stickies, even though they can't possibly show
up for anyone. This commit fixes that.

r2/r2/controllers/api.py

@@ -1636,6 +1636,9 @@ class ApiController(RedditController):
         if not isinstance(thing, Link):
             return
 
+        if thing._deleted or thing._spam:
+            abort(400, "Can't sticky a removed or deleted post")
+
         sr = thing.subreddit_slow
 
         if state:

r2/r2/lib/pages/pages.py

@@ -5290,6 +5290,7 @@ class LinkCommentsSettings(Templated):
             (c.user_is_admin or
                 self.sr.is_moderator_with_perms(c.user, "posts"))
         )
+        self.can_sticky = self.can_edit and not (link._deleted or link._spam)
         self.sort = sort
         self.suggested_sort = suggested_sort
 

r2/r2/templates/linkcommentssettings.html

@@ -112,7 +112,7 @@
   %endif
 %endif
 
-%if thing.can_edit:
+%if thing.can_sticky:
   %if thing.stickied:
     ${ynbutton(_("unsticky this post"), _("unstickied"), "set_subreddit_sticky",
       hidden_data=dict(id=thing.link._fullname, state=False),