Fix mallformed (nullish) messages handling (#4347)

Co-authored-by: Koen Kanters <koenkanters94@gmail.com>

lib/extension/frontend.js

@@ -80,8 +80,10 @@ class Frontend extends Extension {
 
     onWebSocketConnection(ws) {
         ws.on('message', (message) => {
-            const {topic, payload} = utils.parseJSON(message, message);
-            this.mqtt.onMessage(`${this.mqttBaseTopic}/${topic}`, stringify(payload));
+            if (message) {
+                const {topic, payload} = utils.parseJSON(message, message);
+                this.mqtt.onMessage(`${this.mqttBaseTopic}/${topic}`, stringify(payload));
+            }
         });
 
         for (const [key, value] of this.retainedMessages) {

lib/extension/publish.js

@@ -125,10 +125,14 @@ class EntityPublish extends Extension {
                     json = {state: message};
                 } else {
                     logger.error(`Invalid JSON '${message}', skipping...`);
+                    return false;
                 }
             }
         }
-
+        if (!json) {
+            logger.error(`Invalid JSON '${message}', skipping...`);
+            return;
+        }
 
         /**
          * Home Assistant always publishes 'state', even when e.g. only setting

lib/mqtt.js

@@ -91,7 +91,7 @@ class MQTT extends events.EventEmitter {
     }
 
     onMessage(topic, message) {
-        this.emit('message', {topic, message: message.toString()});
+        this.emit('message', {topic, message: message + ''});
     }
 
     isConnected() {

test/frontend.test.js

@@ -139,6 +139,10 @@ describe('Frontend', () => {
             { retain: false, qos: 0 },
             expect.any(Function)
         );
+        mockWSClient.events.message(undefined);
+        mockWSClient.events.message("");
+        mockWSClient.events.message(null);
+        await flushPromises();
 
         // Received message on socket
         expect(mockWSClient.implementation.send).toHaveBeenCalledTimes(4);

test/publish.test.js

@@ -66,6 +66,18 @@ describe('Publish', () => {
         expect(MQTT.publish.mock.calls[0][2]).toStrictEqual({"qos": 0, "retain": false});
     });
 
+    it('Should corretly handle mallformed messages', async () => {
+        await MQTT.events.message('zigbee2mqtt/foo', undefined);
+        await MQTT.events.message('zigbee2mqtt/foo', null);
+        await MQTT.events.message('zigbee2mqtt/foo', "");
+
+        await MQTT.events.message('zigbee2mqtt/bulb_color/set', undefined);
+        await MQTT.events.message('zigbee2mqtt/bulb_color/set', null);
+        await MQTT.events.message('zigbee2mqtt/bulb_color/set', "");
+        await flushPromises();
+        expectNothingPublished();
+    });
+
     it('Should publish messages to zigbee devices when there is no converters', async () => {
         await MQTT.events.message('zigbee2mqtt/bulb_color/set', stringify({brightness_no: '200'}));
         await flushPromises();