src/vs/platform/workspace/common/workspace.ts/isSingleFolderWorkspaceIdentifier
export function isSingleFolderWorkspaceIdentifier(obj: unknown): obj is ISingleFolderWorkspaceIdentifier {
	const singleFolderIdentifier = obj as ISingleFolderWorkspaceIdentifier | undefined;

	return typeof singleFolderIdentifier?.id === 'string' && URI.isUri(singleFolderIdentifier.uri);
}