BUGFIX: Remove race condition in watchNodeInformationChanges

By using the `takeLatest` higher-order saga, this changes makes sure
that all attempts at fetching additional node metadata are cancelled
once a new node-related action is triggered.

Without this stale `fetchAdditionalNodeMetadata` calls may corrupt the
in-memory node cache, which leads to further problems downstream.

This became apparent after #3756.

packages/neos-ui-sagas/src/CR/Policies/index.js

@@ -1,4 +1,4 @@
-import {select, take, put, fork} from 'redux-saga/effects';
+import {select, take, put, fork, takeLatest} from 'redux-saga/effects';
 
 import {actions, actionTypes, selectors} from '@neos-project/neos-ui-redux-store';
 import backend from '@neos-project/neos-ui-backend-connector';
@@ -22,8 +22,7 @@ function * fetchAdditionalNodeMetadata(nodesWithoutAdditionalMetadata) {
 }
 
 export function * watchNodeInformationChanges() {
-    while (true) {
-        const action = yield take([actionTypes.CR.Nodes.MERGE, actionTypes.CR.Nodes.ADD, actionTypes.CR.Nodes.SET_STATE]);
+    yield takeLatest([actionTypes.CR.Nodes.MERGE, actionTypes.CR.Nodes.ADD, actionTypes.CR.Nodes.SET_STATE], function * (action) {
         const nodeMap = (action.type === actionTypes.CR.Nodes.SET_STATE) ? action.payload.nodes : action.payload.nodeMap;
         const state = yield select();
 
@@ -39,10 +38,10 @@ export function * watchNodeInformationChanges() {
         });
 
         if (nodesWithoutAdditionalMetadata.length === 0) {
-            continue;
+            return;
         }
 
         yield fork(fetchAdditionalNodeMetadata, nodesWithoutAdditionalMetadata);
-    }
+    });
 }