Merge all changes

src/Concelier/__Connectors/StellaOps.Concelier.Connector.Astra/AstraConnector.cs

@@ -185,6 +185,11 @@ public sealed class AstraConnector : IFeedConnector
     /// </remarks>
     private async Task<string> FetchOvalDatabaseAsync(string version, CancellationToken cancellationToken)
     {
+        if (_fetchService is null || _rawDocumentStorage is null)
+        {
+            throw new InvalidOperationException("Fetch and raw document storage services are required for OVAL database fetch");
+        }
+
         var uri = _options.BuildOvalDatabaseUri(version);
 
         _logger.LogDebug("Fetching OVAL database for Astra Linux {Version} from {Uri}", version, uri);
@@ -197,18 +202,24 @@ public sealed class AstraConnector : IFeedConnector
 
         var result = await _fetchService.FetchAsync(request, cancellationToken).ConfigureAwait(false);
 
-        if (!result.IsSuccess || result.Document is null)
+        if (result is null || !result.IsSuccess || result.Document is null)
         {
             throw new InvalidOperationException($"Failed to fetch OVAL database for version {version}");
         }
 
-        if (!result.Document.PayloadId.HasValue)
+        var document = result.Document;
+
+        if (!document.PayloadId.HasValue)
         {
             throw new InvalidOperationException($"OVAL database document for version {version} has no payload");
         }
 
         // Download the raw XML content
-        var payloadBytes = await _rawDocumentStorage.DownloadAsync(result.Document.PayloadId.Value, cancellationToken).ConfigureAwait(false);
+        var payloadBytes = await _rawDocumentStorage.DownloadAsync(document.PayloadId.Value, cancellationToken).ConfigureAwait(false);
+        if (payloadBytes is null)
+        {
+            throw new InvalidOperationException($"OVAL database payload for version {version} not found");
+        }
         return System.Text.Encoding.UTF8.GetString(payloadBytes);
     }