[FIX] Sensible error message when no text to add was given
[FIX] Sensible error message when no text to add was given

Change-Id: I86c3bd796db9d335e2a860784d7c483ca374c053

npdoty/pywikibot,magul/pywikibot-core,hasteur/g13bot_tools_new,wikimedia/pywikibot-core,hasteur/g13bot_tools_new,TridevGuha/pywikibot-core,Darkdadaah/pywikibot-core,magul/pywikibot-core,valhallasw/pywikibot-core,darthbhyrava/pywikibot-local,happy5214/pywikibot-core,icyflame/batman,h4ck3rm1k3/pywikibot-core,Darkdadaah/pywikibot-core,hasteur/g13bot_tools_new,wikimedia/pywikibot-core,xZise/pywikibot-core,jayvdb/pywikibot-core,jayvdb/pywikibot-core,npdoty/pywikibot,trishnaguha/pywikibot-core,emijrp/pywikibot-core,h4ck3rm1k3/pywikibot-core,smalyshev/pywikibot-core,PersianWikipedia/pywikibot-core,happy5214/pywikibot-core,VcamX/pywikibot-core