TypeError: Cannot use 'in' operator to search for 'TempRefrigerator_C'
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**Describe The Bug:**
When adding a GF-B590PL refrigerator, the subject error is thrown.

**To Reproduce:**
Fresh install of HomeBridge, add plugin, have fridge included in accessories

**Expected behavior:**
Fridge to add successfully

**Logs:**

Starting to advertise 'Homebridge 7273 6670' using bonjour-hap backend!
[07/09/2021, 2:12:40 pm] Homebridge v1.3.4 (Homebridge 7273) is running on port 51601.

<< I've excluded the logs for my washer/dryer here, happy to provide if they'll add value, but I have no issues with those >>

[07/09/2021, 2:12:50 pm] [LGThinQ] Adding new accessory: Refrigerator
(node:30564) UnhandledPromiseRejectionWarning: TypeError: Cannot use 'in' operator to search for 'TempRefrigerator_C' in undefined
    at DeviceModel.monitoringValueMapping (/usr/lib/node_modules/homebridge-lg-thinq/src/lib/DeviceModel.ts:160:14)
    at Refrigerator.createThermostat (/usr/lib/node_modules/homebridge-lg-thinq/src/devices/Refrigerator.ts:212:53)
    at Refrigerator.createThermostat (/usr/lib/node_modules/homebridge-lg-thinq/src/v1/devices/Refrigerator.ts:12:18)
    at new Refrigerator (/usr/lib/node_modules/homebridge-lg-thinq/src/devices/Refrigerator.ts:35:31)
    at new Refrigerator (/usr/lib/node_modules/homebridge-lg-thinq/src/v1/devices/Refrigerator.ts:5:1)
    at LGThinQHomebridgePlatform.discoverDevices (/usr/lib/node_modules/homebridge-lg-thinq/src/platform.ts:125:25)
    at processTicksAndRejections (internal/process/task_queues.js:95:5)
    at HomebridgeAPI.<anonymous> (/usr/lib/node_modules/homebridge-lg-thinq/src/platform.ts:53:7)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:30564) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:30564) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.


**Plugin Config:**

{
    "bridge": {
        "name": "Homebridge 7273",
        "username": "----",
        "port": 51601,
        "pin": "----"
    },
    "accessories": [],
    "platforms": [
        {
            "name": "Config",
            "port": 8581,
            "platform": "config"
        },
        {
            "country": "AU",
            "language": "en-AU",
            "auth_mode": "token",
            "refresh_token": "----",
            "username": "----",
            "password": "----",
            "devices": [
                {
                    "id": "1d6c7777-bf6c-1353-95a9-24e853db5e46",
                    "name": "Dryer",
                    "type": "DRYER"
                },
                {
                    "id": "d0f9c37a-42b9-1879-a103-dc039838787d",
                    "name": "Washer",
                    "type": "WASHER",
                    "washer_trigger": true,
                    "washer_door_lock": true
                },
                {
                    "id": "d74ed200-a234-11eb-8ae0-0051eda83e50",
                    "name": "Refrigerator",
                    "type": "REFRIGERATOR",
                    "ref_express_freezer": false,
                    "ref_express_fridge": false,
                    "ref_eco_friendly": false
                }
            ],
            "refresh_interval": 60,
            "thinq1": true,
            "platform": "LGThinQ"
        }
    ]
}

**Screenshots:**

N/A

**Environment:**

* **Plugin Version**: 1.1.4
* **Homebridge Version**: 1.3.4
* **Node.js Version**: 14.17.6
* **NPM Version**: 6.14.15
* **Operating System**: Debian 11 in a Proxmox VM
