correct declaration of env object/dic/lookup

Dont use `subscriptionIdentifier` if broker doesnt support it

packages/node_modules/@node-red/nodes/core/network/10-mqtt.js

@@ -697,7 +697,8 @@ module.exports = function(RED) {
                 node.options.rejectUnauthorized = (node.verifyservercert == "true" || node.verifyservercert === true);
             }
         }
-
+        node.v5 = () => node.options && node.options.protocolVersion == 5
+        node.subscriptionIdentifiersAvailable = () => node.v5() && node.serverProperties && node.serverProperties.subscriptionIdentifiersAvailable
         n.autoConnect = n.autoConnect === "false" || n.autoConnect === false ? false : true;
         node.setOptions(n, true);
 
@@ -920,7 +921,12 @@ module.exports = function(RED) {
             };
             node.subscriptions[topic][ref] = sub;
             if (node.connected) {
+                const subIdsAvailable = node.subscriptionIdentifiersAvailable()
                 node._clientOn('message',sub.handler);
+                // if the broker doesn't support subscription identifiers (e.g. AWS core), then don't send them
+                if (options.properties && options.properties.subscriptionIdentifier && subIdsAvailable !== true) {
+                    delete options.properties.subscriptionIdentifier
+                }
                 node.client.subscribe(topic, options);
             }
         };

packages/node_modules/@node-red/runtime/lib/flows/Flow.js

@@ -808,7 +808,7 @@ function handlePreRoute(flow, sendEvent, reportError) {
             return;
         } else if (err !== false) {
             sendEvent.destination.node = flow.getNode(sendEvent.destination.id);
-            if (sendEvent.destination.node) {
+            if (sendEvent.destination.node && typeof sendEvent.destination.node === 'object') {
                 if (sendEvent.cloneMessage) {
                     sendEvent.msg = redUtil.cloneMessage(sendEvent.msg);
                 }

packages/node_modules/@node-red/runtime/lib/flows/Subflow.js

@@ -119,7 +119,7 @@ class Subflow extends Flow {
         this.templateCredentials = credentials.get(subflowDef.id) || {};
         this.instanceCredentials = credentials.get(id) || {};
 
-        var env = [];
+        var env = {}; 
         if (this.subflowDef.env) {
             this.subflowDef.env.forEach(e => {
                 env[e.name] = e;