Fix all typescript type issues

src/App.tsx

@@ -5,14 +5,19 @@ import ReactFlow, {
   applyEdgeChanges,
   applyNodeChanges,
   addEdge,
+  Node,
+  Edge,
+  NodeChange,
+  EdgeChange,
+  Connection,
 } from 'reactflow';
 
 // we have to import the React Flow styles for it to work
 import 'reactflow/dist/style.css';
 
-const initialEdges = [];
+const initialEdges: Edge[] = [];
 
-const initialNodes = [
+const initialNodes: Node[] = [
   {
     id: '1',
     data: { label: 'Hello' },
@@ -31,16 +36,19 @@ const Flow = () => {
   const [edges, setEdges] = useState(initialEdges);
 
   const onNodesChange = useCallback(
-    changes => setNodes(nds => applyNodeChanges(changes, nds)),
+    (changes: NodeChange[]) =>
+      setNodes((nds: Node[]) => applyNodeChanges(changes, nds)),
     [],
   );
   const onEdgesChange = useCallback(
-    changes => setEdges(eds => applyEdgeChanges(changes, eds)),
+    (changes: EdgeChange[]) =>
+      setEdges((eds: Edge[]) => applyEdgeChanges(changes, eds)),
     [],
   );
 
   const onConnect = useCallback(
-    params => setEdges(eds => addEdge(params, eds)),
+    (params: Edge | Connection) =>
+      setEdges((eds: Edge[]) => addEdge(params, eds)),
     [],
   );