This is bug exist from the first time this property introduced and still exit in latest build too

just drop TSiLang on new project, make StoreAsUTF8 property to true, double click on TSilang component, and try to write any thing even in English, close the editor and when asking to save click yes, then IDE will disappear completely
i have Tried that in many project but with simple project that contain TsiLang it exits too.
Regards,