Add 'Vote not found'

vedia.rb

@@ -319,6 +319,9 @@ end
 get '/votes/:id' do
   require_login
   find_vote
+  if not @vote
+    erb :votes_show_unknown
+  else
     case @vote.state
     when 'draft'
       if @vote.users.exists?(current_user.id)
@@ -331,6 +334,7 @@ get '/votes/:id' do
     when 'closed'
       erb :votes_show_closed
     end
+  end
 end
 
 get '/votes/:id/edit' do

views/votes_show_unknown.erb

@@ -0,0 +1,3 @@
+<div class="mb-5">
+  <h1><%= _("Vote not found...") %></h1>
+</div>