Fix stack underflows when yielding twice
Fix stack underflows when yielding twice

Also, refactor GDScriptFunctionState::_signal_callback, removing some excessive repetition.
Fixes #30269.

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