Fix crash when unsharing a range that is not shared
Fix crash when unsharing a range that is not shared

Added a guard to Range::_unref_shared to prevent it from doing anything
in the event that shared is null.

Fixes Issue: #11521

okamstudio/godot,Shockblast/godot,Shockblast/godot,Shockblast/godot,Paulloz/godot,godotengine/godot,Valentactive/godot,Zylann/godot,honix/godot,guilhermefelipecgs/godot,sanikoyes/godot,MarianoGnu/godot,DmitriySalnikov/godot,josempans/godot,guilhermefelipecgs/godot,Faless/godot,Paulloz/godot,okamstudio/godot,Faless/godot,RandomShaper/godot,vkbsb/godot,mcanders/godot,vkbsb/godot,Faless/godot,BastiaanOlij/godot,firefly2442/godot,ageazrael/godot,okamstudio/godot,Brickcaster/godot,FateAce/godot,guilhermefelipecgs/godot,okamstudio/godot,vnen/godot,BastiaanOlij/godot,FateAce/godot,vnen/godot,godotengine/godot,ageazrael/godot,Zylann/godot,n-pigeon/godot,Valentactive/godot,DmitriySalnikov/godot,vkbsb/godot,honix/godot,FateAce/godot,sanikoyes/godot,Faless/godot,vnen/godot,pkowal1982/godot,vnen/godot,DmitriySalnikov/godot,ZuBsPaCe/godot,okamstudio/godot,Valentactive/godot,mcanders/godot,Shockblast/godot,vkbsb/godot,pkowal1982/godot,vnen/godot,MarianoGnu/godot,n-pigeon/godot,vkbsb/godot,MarianoGnu/godot,groud/godot,ageazrael/godot,NateWardawg/godot,godotengine/godot,Paulloz/godot,Brickcaster/godot,sanikoyes/godot,NateWardawg/godot,zicklag/godot,BastiaanOlij/godot,ex/godot,godotengine/godot,ex/godot,ex/godot,groud/godot,Brickcaster/godot,honix/godot,Brickcaster/godot,guilhermefelipecgs/godot,sanikoyes/godot,DmitriySalnikov/godot,ex/godot,ZuBsPaCe/godot,Zylann/godot,pkowal1982/godot,ZuBsPaCe/godot,okamstudio/godot,vnen/godot,n-pigeon/godot,Shockblast/godot,BastiaanOlij/godot,groud/godot,RandomShaper/godot,ZuBsPaCe/godot,Paulloz/godot,akien-mga/godot,zicklag/godot,firefly2442/godot,guilhermefelipecgs/godot,ZuBsPaCe/godot,groud/godot,akien-mga/godot,honix/godot,FateAce/godot,godotengine/godot,MarianoGnu/godot,NateWardawg/godot,josempans/godot,MarianoGnu/godot,RandomShaper/godot,firefly2442/godot,firefly2442/godot,sanikoyes/godot,ageazrael/godot,vkbsb/godot,zicklag/godot,Paulloz/godot,Valentactive/godot,RandomShaper/godot,akien-mga/godot,firefly2442/godot,Shockblast/godot,Faless/godot,akien-mga/godot,Brickcaster/godot,ageazrael/godot,groud/godot,NateWardawg/godot,honix/godot,ZuBsPaCe/godot,firefly2442/godot,firefly2442/godot,vkbsb/godot,n-pigeon/godot,Zylann/godot,vnen/godot,MarianoGnu/godot,NateWardawg/godot,Brickcaster/godot,RandomShaper/godot,Valentactive/godot,n-pigeon/godot,groud/godot,FateAce/godot,okamstudio/godot,sanikoyes/godot,pkowal1982/godot,ageazrael/godot,firefly2442/godot,sanikoyes/godot,Faless/godot,guilhermefelipecgs/godot,akien-mga/godot,MarianoGnu/godot,guilhermefelipecgs/godot,josempans/godot,mcanders/godot,godotengine/godot,Zylann/godot,NateWardawg/godot,pkowal1982/godot,zicklag/godot,RandomShaper/godot,Paulloz/godot,okamstudio/godot,Zylann/godot,ageazrael/godot,DmitriySalnikov/godot,ex/godot,akien-mga/godot,josempans/godot,mcanders/godot,DmitriySalnikov/godot,zicklag/godot,pkowal1982/godot,MarianoGnu/godot,FateAce/godot,ex/godot,Valentactive/godot,zicklag/godot,akien-mga/godot,BastiaanOlij/godot,ex/godot,NateWardawg/godot,mcanders/godot,pkowal1982/godot,Valentactive/godot,sanikoyes/godot,RandomShaper/godot,Faless/godot,BastiaanOlij/godot,honix/godot,okamstudio/godot,ZuBsPaCe/godot,BastiaanOlij/godot,josempans/godot,Valentactive/godot,n-pigeon/godot,Brickcaster/godot,NateWardawg/godot,BastiaanOlij/godot,josempans/godot,josempans/godot,akien-mga/godot,n-pigeon/godot,vnen/godot,Paulloz/godot,Shockblast/godot,Faless/godot,godotengine/godot,okamstudio/godot,ZuBsPaCe/godot,josempans/godot,vkbsb/godot,pkowal1982/godot,mcanders/godot,DmitriySalnikov/godot,Zylann/godot,Zylann/godot,NateWardawg/godot,godotengine/godot,Shockblast/godot,ex/godot,guilhermefelipecgs/godot