Fix error when linking already linked issue to epic

changelogs/unreleased/32557-fix-error-adding-already-linked-issue.yml

+---
+title: Fix error when linking already linked issue to epic
+merge_request: 21213
+author:
+type: fixed

ee/app/assets/javascripts/related_items_tree/store/actions.js

@@ -308,7 +308,7 @@ export const receiveAddItemSuccess = ({ dispatch, commit, getters }, { rawItems
   dispatch('setItemInputValue', '');
   dispatch('toggleAddItemForm', { toggleState: false });
 };
-export const receiveAddItemFailure = ({ commit }, { itemAddFailureType }) => {
+export const receiveAddItemFailure = ({ commit }, { itemAddFailureType } = {}) => {
   commit(types.RECEIVE_ADD_ITEM_FAILURE, { itemAddFailureType });
 };
 export const addItem = ({ state, dispatch, getters }) => {

ee/spec/javascripts/related_items_tree/store/actions_spec.js

@@ -930,6 +930,22 @@ describe('RelatedItemTree', () => {
             done,
           );
         });
+
+        it('should set `state.itemAddInProgress` to false, no payload', done => {
+          testAction(
+            actions.receiveAddItemFailure,
+            undefined,
+            {},
+            [
+              {
+                type: types.RECEIVE_ADD_ITEM_FAILURE,
+                payload: { itemAddFailureType: undefined },
+              },
+            ],
+            [],
+            done,
+          );
+        });
       });
 
       describe('addItem', () => {