Unable to use StorageAccount.GetKeys as expression because it returns null

[davidfowl]

var storageVolume = new StorageAccount("storageVolume")
{
    Sku = new StorageSku() { Name = StorageSkuName.StandardLrs },
    Kind = StorageKind.StorageV2,
    LargeFileSharesState = LargeFileSharesState.Enabled
};

BicepValue<string> keys0Value = storageVolume.GetKeys()[0].Value?.Value;

The above returns a null ref. I'm trying to use this in an expression (listKeys()[0].value) and was able to work around it by doing the following:

var keysExpr = storageVolume.GetKeys()[0].Compile();
var keyValue = new MemberExpression(keysExpr, "value");