Fix a crash when using markers with a PieChart
Fix a crash when using markers with a PieChart

hanquochan/Charts,convergeeducacao/Charts,boluomeng/Charts,duanhjlt/ios-charts,franqueli/ios-charts,MAARK/Charts,FreddyZeng/Charts,jesseXu/Charts,aelam/Charts,jesseXu/Charts,Shannon-s-Dreamland/Charts,ekohe/ios-charts,danielgindi/Charts,danielgindi/Charts,liuxuan30/Charts,danielgindi/ios-charts,jjatie/Charts,Eflet/Charts,icecrystal23/ios-charts,dtrauger/Charts,danielallsopp/Charts,duanhjlt/ios-charts,liuxuan30/Charts,Eflet/Charts,aelam/Charts,dtrauger/Charts,ConcepterDev/ios-charts,aelam/Charts,summerlove57/ios-charts,jjatie/Charts,jum/Charts,liuxuan30/ios-charts,icecrystal23/ios-charts,franqueli/ios-charts,SBGMobile/Charts,duanhjlt/ios-charts,dtrauger/Charts,danielgindi/ios-charts,LiveHappier/Charts,jum/Charts,SBGMobile/Charts,MAARK/Charts,hanquochan/Charts,jjatie/Charts,summerlove57/ios-charts,FreddyZeng/Charts,gjpc/ios-charts,SereivoanYong/Charts,jjatie/Charts,jum/Charts,ekohe/ios-charts,hanquochan/Charts,SereivoanYong/Charts,SereivoanYong/Charts,convergeeducacao/Charts,MAARK/Charts,LiveHappier/Charts,LiveHappier/Charts,liuxuan30/Charts,boluomeng/Charts,dtrauger/Charts,shujucn/ios-charts,ConcepterDev/ios-charts,Shannon-s-Dreamland/Charts,hanquochan/Charts,liuxuan30/ios-charts,boluomeng/Charts,liuxuan30/ios-charts,FreddyZeng/Charts,icecrystal23/ios-charts,Eflet/Charts,gjpc/ios-charts,ekohe/ios-charts,icecrystal23/ios-charts,summerlove57/ios-charts,danielgindi/ios-charts,liuxuan30/Charts,gjpc/ios-charts,SBGMobile/Charts,liuxuan30/ios-charts,shujucn/ios-charts,jesseXu/Charts,boluomeng/Charts,danielgindi/Charts,Eflet/Charts,danielgindi/Charts,ConcepterDev/ios-charts,shujucn/ios-charts,danielgindi/ios-charts,FreddyZeng/Charts,danielallsopp/Charts,jum/Charts,franqueli/ios-charts,MAARK/Charts