Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- `Gemfile.lock`:
  No real conflict, glitch-soc-only dependency (redcarpet) too close to an
  upstream one (rdf-normalize)
- `README.md`:
  we have different READMEs, discarded upstream's changes
- `app/views/admin/custom_emojis/index.html.haml`:
  No real conflict, different context because of glitch-soc theming
- `lib/mastodon/statuses_cli.rb`:
  Upstream added code to keep bookmarked statuses, we were already doing so
  with slightly different code. Discarded upstream's changes.
- `package.json`:
  No real conflict, glitch-soc-only dependency (favico.js) too close to
  an upstream one

app/validators/vote_validator.rb

@@ -4,10 +4,18 @@ class VoteValidator < ActiveModel::Validator
   def validate(vote)
     vote.errors.add(:base, I18n.t('polls.errors.expired')) if vote.poll.expired?
 
+    vote.errors.add(:base, I18n.t('polls.errors.invalid_choice')) if invalid_choice?(vote)
+
     if vote.poll.multiple? && vote.poll.votes.where(account: vote.account, choice: vote.choice).exists?
       vote.errors.add(:base, I18n.t('polls.errors.already_voted'))
     elsif !vote.poll.multiple? && vote.poll.votes.where(account: vote.account).exists?
       vote.errors.add(:base, I18n.t('polls.errors.already_voted'))
     end
   end
+
+  private
+
+  def invalid_choice?(vote)
+    vote.choice.negative? || vote.choice >= vote.poll.options.size
+  end
 end