While running unit tests in backend, connector crashes becuase not interface property

[mStirner]

[2024.01.25 - 11:20.31.963][warn][system] Backend http://127.0.0.1:8080 not reachable, retry attempt 7...
[2024.01.25 - 11:20.32.891][info][forwarder/mqtt] Connected to ws://127.0.0.1:8080/api/mqtt?x-auth-token=
[2024.01.25 - 11:20.32.893][info][forwarder/mqtt] Client connected to tcp://127.0.0.1:1883
[2024.01.25 - 11:20.32.975][debug][system] WebSocket connected to: ws://127.0.0.1:8080/api/events?x-auth-token=
[2024.01.25 - 11:20.32.975][debug][system] Read to bridge traffic
[2024.01.25 - 11:20.32.975][debug][system] No enabled devices returned, nothing to bridge...
[2024.01.25 - 11:20.36.734][debug][system] Device in backend added {
  _id: '65818918d32dad8dab53e433',
  name: 'SmartMeter',
  interfaces: [
    {
      _id: '6581c55abc21a0a3122b9998',
      type: 'ETHERNET',
      description: 'WebSocket API',
      settings: [Object],
      adapter: [Array]
    }
  ],
  room: '62a4bc8bd9256b5e8d6988a0',
  icon: 'fa-solid fa-gauge-high',
  labels: [ 'test=true', 'protected=false', 'foo=bar' ],
  timestamps: { created: 1706178036728, updated: null },
  enabled: true
}
[2024.01.25 - 11:20.36.736][debug][system] Bridge ws://127.0.0.1:8080/api/devices/65818918d32dad8dab53e433/interfaces/6581c55abc21a0a3122b9998 <-> tcp://192.168.2.155:8080
[2024.01.25 - 11:20.36.853][debug][system] Device in backend updated {
  _id: '65818918d32dad8dab53e433',
  name: 'SaMsUnG FrIdGe',
  interfaces: [
    {
      _id: '6581c55abc21a0a3122b9998',
      type: 'ETHERNET',
      description: 'WebSocket API',
      settings: [Object],
      adapter: [Array]
    }
  ],
  room: '62a4bc8bd9256b5e8d6988a0',
  icon: 'fa-solid fa-gauge-high',
  labels: [ 'test=true', 'protected=true', 'foo=bar' ],
  timestamps: { created: 1706178036728, updated: 1706178036849 },
  enabled: true
}
[2024.01.25 - 11:20.36.854][debug][system] iface 6581c55abc21a0a3122b9998 updated, wait 1.5s
/home/marc/projects/OpenHaus/connector/handler.js:86
                    device.interfaces.forEach((iface) => {
                           ^

TypeError: Cannot read properties of null (reading 'interfaces')
    at WebSocket.<anonymous> (/home/marc/projects/OpenHaus/connector/handler.js:86:28)
    at WebSocket.emit (node:events:513:28)
    at Receiver.receiverOnMessage (/home/marc/projects/OpenHaus/connector/node_modules/ws/lib/websocket.js:1160:20)
    at Receiver.emit (node:events:513:28)
    at Receiver.dataMessage (/home/marc/projects/OpenHaus/connector/node_modules/ws/lib/receiver.js:528:14)
    at Receiver.getData (/home/marc/projects/OpenHaus/connector/node_modules/ws/lib/receiver.js:446:17)
    at Receiver.startLoop (/home/marc/projects/OpenHaus/connector/node_modules/ws/lib/receiver.js:148:22)
    at Receiver._write (/home/marc/projects/OpenHaus/connector/node_modules/ws/lib/receiver.js:83:10)
    at writeOrBuffer (node:internal/streams/writable:391:12)
    at _write (node:internal/streams/writable:332:10)
[nodemon] app crashed - waiting for file changes before starting...

Accidental run npm run test in the backend folder while the connector was running.

Check for the interface array?
Even with the changes from OpenHausIO/backend#423 a empty interfaces array should exists so this error should never happens. (Perhaps because one interface was delete?)