Improve assert message text
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hglty07/fancytree,Koloto/fancytree,grandmanitou/fancytree,dewhisna/fancytree,hglty07/fancytree,jiangjunt/fancytree,jiangjunt/fancytree,dewhisna/fancytree,Koloto/fancytree,grandmanitou/fancytree,hglty07/fancytree,dewhisna/fancytree,instein2014/JQuery,instein2014/JQuery,Aliccer/fancytree,Mats0/fancytree,HobieCat/fancytree,grandmanitou/fancytree,Mats0/fancytree,jiangjunt/fancytree,spilmert/fancytree,Aliccer/fancytree,spilmert/fancytree,spilmert/fancytree,Aliccer/fancytree,HobieCat/fancytree,HobieCat/fancytree,Koloto/fancytree