How to process data with mixed values

Hi,
Got this error while running my plugin on a design.

Error: in postMessage: Cannot unwrap symbol Figma

here is the piece of code where the error occurs

figma.ui.onmessage = async (msg) => {
	/**
	 * The function `readDesign` reads the design data from the current page in Figma and sends it to the
	 * UI.
	 */
	const readDesign = async (
		selections: {id: string; name: string; isSelected: string}[],
	) => {
	           .....(code)
                   const getPages = figma.currentPage.findAll((node) =>
			selectedPagesId.includes(node.id),
		);
		const data: any = {};
		for (const i of getPages) {
			if (i.visible) {
				data[i.name] = await extractData(i);
			}
			console.log("data: ", data);
		}
                ......(code)
               figma.ui.postMessage({
			type: "readDesign",
			data: data,
			client: (user.name + user.id).toString(),
			system: "M3",
		});
}

I have referred this link, from where I got to know that this error occurs when the node property is a mix of multiple values.

Any suggestions on how to process this type of data?

Thanks