Dispatcher: fix possible crash when no document (#7716)

frontend/dispatcher.lua

@@ -617,6 +617,8 @@ arguments are:
 function Dispatcher:execute(ui, settings, gesture)
     for k, v in pairs(settings) do
         if settingsList[k] ~= nil and (settingsList[k].conditions == nil or settingsList[k].conditions == true) then
+            -- Be sure we don't send a document setting event if there's not yet or no longer a document
+            if ui.document or (not settingsList[k].paging and not settingsList[k].rolling) then
                 if settingsList[k].category == "none" then
                     if settingsList[k].arg ~= nil then
                         ui:handleEvent(Event:new(settingsList[k].event, settingsList[k].arg))
@@ -651,5 +653,6 @@ function Dispatcher:execute(ui, settings, gesture)
             end
         end
     end
+end
 
 return Dispatcher