feat(deletion): add onBeforeDelete handler

packages/svelte/src/lib/store/index.ts

@@ -215,11 +215,12 @@ export function createStore({
       const selectedNodes = nodes.filter((node) => node.selected);
       const selectedEdges = edges.filter((edge) => edge.selected);
 
-      const { matchingNodes, matchingEdges } = getElementsToRemove<Node, Edge>({
+      const { nodes: matchingNodes, edges: matchingEdges } = getElementsToRemove({
         nodesToRemove: selectedNodes,
         edgesToRemove: selectedEdges,
         nodes,
-        edges
+        edges,
+        onBeforeDelete: get(store.onbeforedelete)
       });
 
       if (matchingNodes.length || matchingEdges.length) {

packages/svelte/src/lib/store/initial-store.ts

@@ -22,7 +22,8 @@ import {
   type OnConnect,
   type OnConnectStart,
   type OnConnectEnd,
-  type NodeLookup
+  type NodeLookup,
+  type OnBeforeDelete
 } from '@xyflow/system';
 
 import DefaultNode from '$lib/components/nodes/DefaultNode.svelte';
@@ -148,6 +149,7 @@ export const getInitialStore = ({
     onedgecreate: writable<OnEdgeCreate>(undefined),
     onconnect: writable<OnConnect>(undefined),
     onconnectstart: writable<OnConnectStart>(undefined),
-    onconnectend: writable<OnConnectEnd>(undefined)
+    onconnectend: writable<OnConnectEnd>(undefined),
+    onbeforedelete: writable<OnBeforeDelete>(undefined)
   };
 };