An error occured during polling state on v5.0.15 
**Describe the bug**
After updating to version v5.0.15 and restarting Homebridge I get the following log output:

```
[27.11.2020, 09:37:17] [FritzPlatform] Smarthome: An error occured during polling state (smarthome)
[27.11.2020, 09:37:17] [FritzPlatform] TypeError: Cannot read property '$' of undefined
    at /usr/local/lib/node_modules/homebridge-fritz-platform/src/helper/deviceHandler.js:3013:20
    at Array.map (<anonymous>)
    at refreshSmarthome (/usr/local/lib/node_modules/homebridge-fritz-platform/src/helper/deviceHandler.js:3002:40)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (internal/process/task_queues.js:93:5)
    at poll (/usr/local/lib/node_modules/homebridge-fritz-platform/src/helper/deviceHandler.js:2784:5)
```

I enabled `debug` but there's no additional context than with `debug` disabled. I'm running a few outlet switches as well as some thermostats.

```
Node.js Version v14.15.0
Npm Version v6.14.8
Homebridge 1.1.6
```

Let me know if you need some additional information :slightly_smiling_face: 