[BUG] - Cant start homebridge after adding plugin
**Describe the bug**
Installed plugin, added config and startup of homebridge has the error below

**Expected behavior**
I'd expect homebridge to start just fine

**Config**
{
            "platform": "Dafang",
            "mqtt": {
                "hostBroker": true,
                "port": 1883,
                "host": "localhost",
                "debug": true,
                "mongoUrl": "mongodb://localhost:27017/mqtt"
            },
            "cameras": [
                {
                    "cameraName": "Window Cam",
                    "cameraRTSPStreamUrl": "rtsp://x.x.x.x:XXXX/unicast",
                    "mqttTopic": "office/window/#",
                    "accessories": [
                        {
                            "name": "Office Window Motion Sensor",
                            "type": "richMotionSensor",
                            "threshold": 300000
                        }
                    ]
                }
            ]
        }

**Logs**
[04/12/2020, 09:31:00] One of your plugins incorrectly registered an external accessory using the platform name (Dafang) and not the plugin identifier. Please report this to the developer!
[04/12/2020, 09:31:00] Window Cam is running on port *****.
[04/12/2020, 09:31:00] Please add [Window Cam] manually in Home app. Setup Code: ***-**-***
[04/12/2020, 09:31:00] SchemaError: Expected `schema` to be an object or boolean
    at Validator.validate (/usr/local/lib/node_modules/homebridge-dafang/node_modules/jsonschema/lib/validator.js:110:11)
    at Object.validate (/usr/local/lib/node_modules/homebridge-dafang/node_modules/mosca/lib/options.js:264:26)
    at new Server (/usr/local/lib/node_modules/homebridge-dafang/node_modules/mosca/lib/server.js:104:34)
    at MQTTBroker.start (/usr/local/lib/node_modules/homebridge-dafang/src/mqtt/broker.js:34:19)
    at MQTTService.initMQTT (/usr/local/lib/node_modules/homebridge-dafang/src/service/mqttService.js:24:17)
    at Dafang.accessories (/usr/local/lib/node_modules/homebridge-dafang/src/dafang.js:106:24)
    at /usr/local/lib/node_modules/homebridge/src/server.ts:415:24
    at new Promise (<anonymous>)
    at Server.loadPlatformAccessories (/usr/local/lib/node_modules/homebridge/src/server.ts:414:12)
    at /usr/local/lib/node_modules/homebridge/src/server.ts:402:28
    at Array.forEach (<anonymous>)
    at Server.loadPlatforms (/usr/local/lib/node_modules/homebridge/src/server.ts:374:27)
    at Server.start (/usr/local/lib/node_modules/homebridge/src/server.ts:153:29)
    at cli (/usr/local/lib/node_modules/homebridge/src/cli.ts:80:10)
    at Object.<anonymous> (/usr/local/lib/node_modules/homebridge/bin/homebridge:17:22)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
    at Module.load (internal/modules/cjs/loader.js:928:32)
    at Function.Module._load (internal/modules/cjs/loader.js:769:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
    at internal/main/run_main_module.js:17:47

**Desktop (please complete the following information):**
 - OS: Raspberry Pi
 - Node Version: v14.15.1

