feat(core): add onError hook

Signed-off-by: braks <78412429+bcakmakoglu@users.noreply.github.com>

packages/core/src/composables/useNode.ts

@@ -11,19 +11,19 @@ export default function useNode<Data = ElementData, CustomEvents extends Record<
   const nodeId = id ?? inject(NodeId, '')
   const nodeEl = inject(NodeRef, null)
 
-  const { findNode, getEdges } = useVueFlow()
+  const { findNode, getEdges, emits } = useVueFlow()
 
   const node = findNode<Data, CustomEvents>(nodeId)
 
   if (!node) {
-    throw new VueFlowError(`Node with id ${nodeId} not found!`, 'useNode')
+    emits.error(new VueFlowError(ErrorCode.NODE_NOT_FOUND, nodeId))
   }
 
   return {
     id: nodeId,
     nodeEl,
     node,
-    parentNode: computed(() => (node.parentNode ? findNode(node.parentNode) : undefined)),
-    connectedEdges: computed(() => getConnectedEdges([node], getEdges.value)),
+    parentNode: computed(() => (node!.parentNode ? findNode(node!.parentNode) : undefined)),
+    connectedEdges: computed(() => getConnectedEdges([node!], getEdges.value)),
   }
 }