Joint2D: Use boolean instead of warning string for validity test
Joint2D: Use boolean instead of warning string for validity test

Those strings are stripped at release there's a false positive that the
bodies are valid, causing a crash.

firefly2442/godot,DmitriySalnikov/godot,pkowal1982/godot,godotengine/godot,ZuBsPaCe/godot,vnen/godot,sanikoyes/godot,ZuBsPaCe/godot,DmitriySalnikov/godot,guilhermefelipecgs/godot,firefly2442/godot,pkowal1982/godot,Valentactive/godot,pkowal1982/godot,vkbsb/godot,Shockblast/godot,DmitriySalnikov/godot,ZuBsPaCe/godot,BastiaanOlij/godot,sanikoyes/godot,Zylann/godot,vnen/godot,sanikoyes/godot,guilhermefelipecgs/godot,Shockblast/godot,firefly2442/godot,Zylann/godot,Faless/godot,BastiaanOlij/godot,DmitriySalnikov/godot,ZuBsPaCe/godot,guilhermefelipecgs/godot,firefly2442/godot,BastiaanOlij/godot,vnen/godot,DmitriySalnikov/godot,firefly2442/godot,ZuBsPaCe/godot,Shockblast/godot,firefly2442/godot,godotengine/godot,josempans/godot,akien-mga/godot,godotengine/godot,vkbsb/godot,vkbsb/godot,sanikoyes/godot,josempans/godot,akien-mga/godot,vnen/godot,Faless/godot,josempans/godot,ZuBsPaCe/godot,akien-mga/godot,guilhermefelipecgs/godot,firefly2442/godot,godotengine/godot,firefly2442/godot,akien-mga/godot,vkbsb/godot,sanikoyes/godot,sanikoyes/godot,godotengine/godot,Valentactive/godot,BastiaanOlij/godot,josempans/godot,Faless/godot,ZuBsPaCe/godot,Zylann/godot,vnen/godot,BastiaanOlij/godot,Zylann/godot,Valentactive/godot,godotengine/godot,pkowal1982/godot,vkbsb/godot,akien-mga/godot,Shockblast/godot,Faless/godot,DmitriySalnikov/godot,DmitriySalnikov/godot,josempans/godot,Faless/godot,Shockblast/godot,BastiaanOlij/godot,vkbsb/godot,guilhermefelipecgs/godot,Shockblast/godot,Zylann/godot,akien-mga/godot,pkowal1982/godot,josempans/godot,vnen/godot,Zylann/godot,Faless/godot,ZuBsPaCe/godot,guilhermefelipecgs/godot,godotengine/godot,guilhermefelipecgs/godot,pkowal1982/godot,sanikoyes/godot,Valentactive/godot,vkbsb/godot,Valentactive/godot,josempans/godot,pkowal1982/godot,josempans/godot,Zylann/godot,BastiaanOlij/godot,vnen/godot,Valentactive/godot,akien-mga/godot,Shockblast/godot,guilhermefelipecgs/godot,Shockblast/godot,pkowal1982/godot,Valentactive/godot,vnen/godot,Zylann/godot,Valentactive/godot,akien-mga/godot,godotengine/godot,Faless/godot,vkbsb/godot,sanikoyes/godot,Faless/godot,BastiaanOlij/godot