Fix empty script interface crash on tscn load.
Fix empty script interface crash on tscn load.

Add fail conditions to protect the visual script function and also fix the initiating cause.

sanikoyes/godot,ZuBsPaCe/godot,josempans/godot,ZuBsPaCe/godot,guilhermefelipecgs/godot,Valentactive/godot,Paulloz/godot,sanikoyes/godot,okamstudio/godot,Valentactive/godot,vnen/godot,josempans/godot,godotengine/godot,Paulloz/godot,guilhermefelipecgs/godot,vnen/godot,vnen/godot,guilhermefelipecgs/godot,groud/godot,BastiaanOlij/godot,Zylann/godot,Zylann/godot,josempans/godot,pkowal1982/godot,ex/godot,godotengine/godot,Valentactive/godot,DmitriySalnikov/godot,Shockblast/godot,MarianoGnu/godot,BastiaanOlij/godot,BastiaanOlij/godot,okamstudio/godot,godotengine/godot,vkbsb/godot,godotengine/godot,Zylann/godot,MarianoGnu/godot,Shockblast/godot,godotengine/godot,okamstudio/godot,okamstudio/godot,Zylann/godot,MarianoGnu/godot,akien-mga/godot,Faless/godot,vnen/godot,ex/godot,vnen/godot,Shockblast/godot,vkbsb/godot,ZuBsPaCe/godot,ex/godot,vkbsb/godot,vkbsb/godot,Valentactive/godot,Valentactive/godot,honix/godot,pkowal1982/godot,Paulloz/godot,sanikoyes/godot,Faless/godot,okamstudio/godot,josempans/godot,honix/godot,groud/godot,DmitriySalnikov/godot,vnen/godot,DmitriySalnikov/godot,pkowal1982/godot,akien-mga/godot,MarianoGnu/godot,BastiaanOlij/godot,DmitriySalnikov/godot,godotengine/godot,sanikoyes/godot,Shockblast/godot,Valentactive/godot,okamstudio/godot,Shockblast/godot,okamstudio/godot,sanikoyes/godot,firefly2442/godot,DmitriySalnikov/godot,DmitriySalnikov/godot,DmitriySalnikov/godot,guilhermefelipecgs/godot,akien-mga/godot,ZuBsPaCe/godot,Zylann/godot,groud/godot,ex/godot,sanikoyes/godot,Zylann/godot,honix/godot,firefly2442/godot,akien-mga/godot,ex/godot,vnen/godot,Faless/godot,Paulloz/godot,okamstudio/godot,Zylann/godot,sanikoyes/godot,pkowal1982/godot,josempans/godot,Paulloz/godot,Faless/godot,BastiaanOlij/godot,Shockblast/godot,vnen/godot,MarianoGnu/godot,honix/godot,groud/godot,Valentactive/godot,ex/godot,josempans/godot,akien-mga/godot,pkowal1982/godot,josempans/godot,akien-mga/godot,pkowal1982/godot,godotengine/godot,okamstudio/godot,Shockblast/godot,Paulloz/godot,Faless/godot,vkbsb/godot,guilhermefelipecgs/godot,Zylann/godot,Paulloz/godot,ZuBsPaCe/godot,okamstudio/godot,sanikoyes/godot,firefly2442/godot,firefly2442/godot,BastiaanOlij/godot,akien-mga/godot,honix/godot,firefly2442/godot,Faless/godot,pkowal1982/godot,Faless/godot,groud/godot,akien-mga/godot,groud/godot,vkbsb/godot,BastiaanOlij/godot,ex/godot,ZuBsPaCe/godot,MarianoGnu/godot,firefly2442/godot,Faless/godot,godotengine/godot,Shockblast/godot,vkbsb/godot,pkowal1982/godot,Valentactive/godot,MarianoGnu/godot,honix/godot,guilhermefelipecgs/godot,vkbsb/godot,firefly2442/godot,BastiaanOlij/godot,guilhermefelipecgs/godot,ZuBsPaCe/godot,MarianoGnu/godot,guilhermefelipecgs/godot,josempans/godot,firefly2442/godot,ZuBsPaCe/godot,ex/godot