src/vs/workbench/contrib/notebook/browser/view/renderers/backLayerWebView.ts/BackLayerWebView/unhideMarkupPreviews
class BackLayerWebView:	async unhideMarkupPreviews(cellIds: readonly string[]) {
		if (this._disposed) {
			return;
		}

		const toUnhide: string[] = [];
		for (const cellId of cellIds) {
			const entry = this.markupPreviewMapping.get(cellId);
			if (entry) {
				if (!entry.visible) {
					entry.visible = true;
					toUnhide.push(cellId);
				}
			} else {
				console.error(`Trying to unhide a preview that does not exist: ${cellId}`);
			}
		}

		this._sendMessageToWebview({
			type: 'unhideMarkupCells',
			ids: toUnhide,
		});
	}