Settings editor rendering breaks for objects with null default values

[RMacfarlane]

Issue Type: Bug

1. Install Azure Account extension

2. Open settings GUI and search for Azure. The ppe setting seems to break rendering, the GUI becomes blank
   

3. Close and try to reopen settings, get
   

The azure.ppe setting:

        "azure.ppe": {
          "type": "object",
          "properties": {
            "portalUrl": {
              "type": "string"
            },
            "publishingProfileUrl": {
              "type": "string"
            },
            "managementEndpointUrl": {
              "type": "string"
            },
            "resourceManagerEndpointUrl": {
              "type": "string"
            },
            "sqlManagementEndpointUrl": {
              "type": "string"
            },
            "sqlServerHostnameSuffix": {
              "type": "string"
            },
            "galleryEndpointUrl": {
              "type": "string"
            },
            "activeDirectoryEndpointUrl": {
              "type": "string"
            },
            "activeDirectoryResourceId": {
              "type": "string"
            },
            "activeDirectoryGraphResourceId": {
              "type": "string"
            },
            "batchResourceId": {
              "type": "string"
            },
            "activeDirectoryGraphApiVersion": {
              "type": "string"
            },
            "storageEndpointSuffix": {
              "type": "string"
            },
            "keyVaultDnsSuffix": {
              "type": "string"
            },
            "azureDataLakeStoreFileSystemEndpointSuffix": {
              "type": "string"
            },
            "azureDataLakeAnalyticsCatalogAndJobEndpointSuffix": {
              "type": "string"
            },
            "validateAuthority": {
              "type": "boolean"
            }
          },
          "default": null,
          "description": "Development setting: The PPE environment for testing."
        }

VS Code version: Code - Insiders 1.47.0-insider (04545fa, 2020-07-02T05:41:12.081Z)
OS version: Darwin x64 18.7.0

[9at8]

Good catch!

[9at8]

@RMacfarlane null is actually not the correct default value type. If you want to allow null as valid type, then the type should be ["object", "null"].

[RMacfarlane]

Since we don't enforce this and it causes the UI to break, I think we should try to get this fix in before the next release.

I'll update the Azure Account extension, though.