function ensureProxies(node, proxies) {
	if (node.server && !proxies.server) {
		proxies.server = createProxy(node.server, true);
	}

	if (node.universal && !proxies.universal) {
		proxies.universal = createProxy(node.universal, false);
	}
}
This function populates the proxies object, if necessary and not already done.
Proxies are used to tweak the code of a file before it's typechecked.
They are needed in two places - when generating the types for a page or layout.
To not do the same work twice, we generate the proxies once and pass them around.

@param {import('types').PageNode} node
@param {Proxies} proxies