Improve error logging for failed JS-to-C++ script conversions

Previously, if a JavaScript function returned a value that failed to
convert to the requested C++ type (e.g., from JS undefined to
std::wstring), the ScriptInterface would fail silently, making debugging
difficult.

This commit improves the error reporting in the script system by logging
the name of the JavaScript function being called when a type conversion
failure occurs. This makes it easier to trace and fix issues arising
from script-side inconsistencies or missing return values.

The improved logging is particularly useful for debugging errors such as
undefined civ values from GetCiv() when used via m_Script.Call<T>().

source/scriptinterface/FunctionWrapper.h

@@ -250,7 +250,7 @@ private:
 			if constexpr (!std::is_same_v<R, IgnoreResult_t>)
 			{
 				if (success)
-					Script::FromJSVal(rq, jsRet, ret);
+					success = Script::FromJSVal(rq, jsRet, ret);
 			}
 			else
 				UNUSED2(ret); // VS2017 complains.