location.getDevices() stalls under certain conditions
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# Bug Report

### Describe the Bug
The `example.ts` script was hanging after logging the "Connected to location" message. I traced through the code and found that it stalls at the `await location.getDevices()` because the message received for `DeviceInfoDocGetList` doesn't pass some of the criteria that's currently required to return data for `getDevices`.

### To Reproduce
Steps to reproduce the behavior:
 - I'm not sure what in my set up is causing the issue. I have a single location with 9 cameras and an offline Ring Alarm base station without any sensors ever connected.
 - Attempt to run example.ts script.
 - Notice it never gets past the "Connected to location" message.

### Expected behavior
- Runs to completion listing the 9 cameras.

### Screenshots/Logs
<!-- ✍️edit: --> If applicable, add screenshots and log output to help explain your problem.

### Additional context
Here's the `DeviceInfoDocGetList` message I get back (IDs redacted):
```
{"msg":"DeviceInfoDocGetList","seq":1,"dst":"aaaa","sessionId":2,"status":-66,"context":{"uiConnection":{"userUuid":"3","accountPermissions":["hub:connect","room:read","masterkey:create","device-state:configure","asset:read","device:create","rule:read","rule:create","beams-device:update","ringnet-security:create","security-user:enable","beams-device:delete","access-code:update","location:update","security-panel:disarm","beams-device:read","room:update","beams-bridge:delete","location-user:read","room:create","monitoring-permit:update","location-user:delete","beams-group:delete","rule:update","mode-settings:update","ringnet-device:create","rule:delete","security-user:disable","ringnet-packet:update","beams-device:create","security-panel:arm","monitoring-settings:update","user.summary:read","asset-command:send","access-code:create","monitoring-settings:read","device-profile:read","beams-group:read","beams-bridge:create","beams-group:create","beams-bridge:read","monitoring-permit:read","rule-list:read","device-profile:update","room:delete","history:read:location","device:delete","location:read","location:delete","device-state:control","beams-bridge:update","location-user-list:read","location-user:update","beams-firmware:read","mode:update","mode:read","beams-group:update","rule:activate","masterkey:read","access-code:delete","location-user:create","alarm-action:send"],"ipAddress":"4.4.4.4","userAgent":"","userPermissions":[]}}}
```

### Environment
 - OS: Windows and Linux
 - Node.js: 12.18.2
 - NPM: 6.14.5
 - ring-client-api: 9.3.5
