SyntaxError: Unexpected token � in JSON at position 0
    at JSON.parse (<anonymous>)
    at MqttClient.<anonymous> (/app/lib/MqttClient.js:145:43)
    at MqttClient.emit (events.js:315:20)
    at MqttClient._handlePublish (/app/node_modules/mqtt/lib/client.js:1277:12)
    at MqttClient._handlePacket (/app/node_modules/mqtt/lib/client.js:410:12)
    at work (/app/node_modules/mqtt/lib/client.js:321:12)
    at Writable.writable._write (/app/node_modules/mqtt/lib/client.js:335:5)
    at doWrite (/app/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:409:139)
    at writeOrBuffer (/app/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:398:5)
    at Writable.write (/app/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:307:11)