fix useNodesData returning undefined in svelte flow

examples/react/src/examples/UseNodesData/index.tsx

@@ -21,7 +21,7 @@ export type UppercaseNode = Node<{ text: string }, 'uppercase'>;
 export type MyNode = TextNode | ResultNode | UppercaseNode;
 
 export function isTextNode(node: any): node is TextNode | UppercaseNode {
-  return node.type === 'text' || node.type === 'uppercase';
+  return !node || !node.type ? false : node.type === 'text' || node.type === 'uppercase';
 }
 
 const nodeTypes = {

examples/svelte/src/routes/examples/usenodesdata/+page.svelte

@@ -6,7 +6,7 @@
 	type ResultNodeType = Node<{}, 'result'>;
 
 	export function isTextNode(node: any): node is TextNodeType | UppercaseNode {
-		return node.type === 'text' || node.type === 'uppercase';
+		return !node || !node.type ? false : node.type === 'text' || node.type === 'uppercase';
 	}
 
 	export type MyNode = TextNodeType | UppercaseNodeType | ResultNodeType;

packages/svelte/src/lib/hooks/useNodesData.ts

@@ -22,6 +22,7 @@ export function useNodesData(nodeIds: any): any {
   const { nodes, nodeLookup } = useStore();
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   let prevNodesData: any[] = [];
+  let initialRun = true;
 
   return derived([nodes, nodeLookup], ([, nodeLookup], set) => {
     const nextNodesData = [];
@@ -39,9 +40,10 @@ export function useNodesData(nodeIds: any): any {
       }
     }
 
-    if (!shallowNodeData(nextNodesData, prevNodesData)) {
-      prevNodesData = nextNodesData;
+    if (!shallowNodeData(nextNodesData, prevNodesData) || initialRun) {
+      prevNodesData = [...nextNodesData];
       set(isArrayOfIds ? nextNodesData : nextNodesData[0] ?? null);
+      initialRun = false;
     }
   });
 }