fix potential infinite loop in show_matching highlighter
fix potential infinite loop in show_matching highlighter

ekie/kakoune,occivink/kakoune,mawww/kakoune,Asenar/kakoune,danr/kakoune,alpha123/kakoune,elegios/kakoune,jjthrash/kakoune,flavius/kakoune,ekie/kakoune,alpha123/kakoune,alexherbo2/kakoune,Somasis/kakoune,alexherbo2/kakoune,xificurC/kakoune,zakgreant/kakoune,zakgreant/kakoune,danr/kakoune,danielma/kakoune,lenormf/kakoune,xificurC/kakoune,danr/kakoune,Somasis/kakoune,elegios/kakoune,alpha123/kakoune,Somasis/kakoune,xificurC/kakoune,alexherbo2/kakoune,flavius/kakoune,zakgreant/kakoune,elegios/kakoune,rstacruz/kakoune,Asenar/kakoune,jkonecny12/kakoune,elegios/kakoune,Asenar/kakoune,alpha123/kakoune,mawww/kakoune,Asenar/kakoune,rstacruz/kakoune,ekie/kakoune,casimir/kakoune,lenormf/kakoune,casimir/kakoune,jkonecny12/kakoune,rstacruz/kakoune,danielma/kakoune,occivink/kakoune,danr/kakoune,ekie/kakoune,zakgreant/kakoune,flavius/kakoune,alexherbo2/kakoune,occivink/kakoune,lenormf/kakoune,occivink/kakoune,casimir/kakoune,mawww/kakoune,danielma/kakoune,jjthrash/kakoune,xificurC/kakoune,jkonecny12/kakoune,jkonecny12/kakoune,rstacruz/kakoune,flavius/kakoune,casimir/kakoune,mawww/kakoune,jjthrash/kakoune,Somasis/kakoune,jjthrash/kakoune,lenormf/kakoune,danielma/kakoune