Fix notifications building from JSON
Fix notifications building from JSON

Sometimes (like in welcome messages), notifications don't have a
'title' property, so we shouldn't assume there is one.

Bug: T139015
Change-Id: I83e480d04e8e09aa9bcb5edef4f56b47d150e199

wikimedia/pywikibot-core,hasteur/g13bot_tools_new,magul/pywikibot-core,hasteur/g13bot_tools_new,happy5214/pywikibot-core,PersianWikipedia/pywikibot-core,wikimedia/pywikibot-core,Darkdadaah/pywikibot-core,npdoty/pywikibot,hasteur/g13bot_tools_new,npdoty/pywikibot,jayvdb/pywikibot-core,happy5214/pywikibot-core,jayvdb/pywikibot-core,Darkdadaah/pywikibot-core,magul/pywikibot-core