Method checkPrepared

src/yvalve/why.cpp:1253–1257

		FB_BOOLEAN fetch(CheckStatusWrapper* status, IMessageMetadata* outMetadata, UCHAR* outBuffer);

		void checkPrepared(ISC_STATUS code = isc_unprepared_stmt) const
		{
			if (!statement)
				Arg::Gds(code).raise();
		}

		void checkCursorOpened() const
		{