Fix some null checks when qBittorrent returns an empty response (#784)

code/backend/Cleanuparr.Infrastructure.Tests/Features/DownloadClient/QBitServiceTests.cs

@@ -247,6 +247,25 @@ public class QBitServiceTests : IClassFixture<QBitServiceFixture>
             result.DeleteFromClient.ShouldBeFalse();
         }
 
+        [Fact]
+        public async Task TorrentListIsNull_ReturnsEmptyResult()
+        {
+            // Arrange
+            const string hash = "test-hash";
+            QBitService sut = _fixture.CreateSut();
+
+            _fixture.ClientWrapper
+                .GetTorrentListAsync(Arg.Any<TorrentListQuery>())
+                .Returns((IReadOnlyList<TorrentInfo>?)null);
+
+            // Act
+            DownloadCheckResult result = await sut.ShouldRemoveFromArrQueueAsync(hash, Array.Empty<string>());
+
+            // Assert
+            result.Found.ShouldBeFalse();
+            result.ShouldRemove.ShouldBeFalse();
+        }
+
         [Fact]
         public async Task TorrentTrackersNotFound_ReturnsEmptyResult()
         {
@@ -1487,6 +1506,23 @@ public class QBitServiceTests : IClassFixture<QBitServiceFixture>
             result.DeleteReason.ShouldBe(DeleteReason.None);
         }
 
+        [Fact]
+        public async Task TorrentListIsNull_ReturnsNotFound()
+        {
+            const string hash = "deleted-hash";
+            QBitService sut = _fixture.CreateSut();
+            SetMalwareBlockerContext();
+
+            _fixture.ClientWrapper
+                .GetTorrentListAsync(Arg.Any<TorrentListQuery>())
+                .Returns((IReadOnlyList<TorrentInfo>?)null);
+
+            BlockFilesResult result = await sut.BlockUnwantedFilesAsync(hash, Array.Empty<string>());
+
+            result.Found.ShouldBeFalse();
+            result.ShouldRemove.ShouldBeFalse();
+        }
+
         [Fact]
         public async Task TrackersNotFound_ReturnsNotFound()
         {

code/backend/Cleanuparr.Infrastructure/Features/DownloadClient/QBittorrent/IQBittorrentClientWrapper.cs

@@ -9,7 +9,7 @@ public interface IQBittorrentClientWrapper : IDisposable
 {
     Task LoginAsync(string username, string password);
     Task<ApiVersion> GetApiVersionAsync();
-    Task<IReadOnlyList<TorrentInfo>> GetTorrentListAsync(TorrentListQuery query);
+    Task<IReadOnlyList<TorrentInfo>?> GetTorrentListAsync(TorrentListQuery query);
     Task<TorrentProperties?> GetTorrentPropertiesAsync(string hash);
     Task<IReadOnlyList<TorrentContent>?> GetTorrentContentsAsync(string hash);
     Task<IReadOnlyList<TorrentTracker>?> GetTorrentTrackersAsync(string hash);

code/backend/Cleanuparr.Infrastructure/Features/DownloadClient/QBittorrent/QBitServiceCB.cs

@@ -15,7 +15,7 @@ public partial class QBitService
     public override async Task<BlockFilesResult> BlockUnwantedFilesAsync(string hash, IReadOnlyList<string> ignoredDownloads)
     {
         TorrentInfo? download = (await _client.GetTorrentListAsync(new TorrentListQuery { Hashes = [hash] }))
-            .FirstOrDefault();
+            ?.FirstOrDefault();
         BlockFilesResult result = new();
 
         if (download is null)

code/backend/Cleanuparr.Infrastructure/Features/DownloadClient/QBittorrent/QBitServiceQC.cs

@@ -15,7 +15,7 @@ public partial class QBitService
     {
         DownloadCheckResult result = new();
         TorrentInfo? download = (await _client.GetTorrentListAsync(new TorrentListQuery { Hashes = [hash] }))
-            .FirstOrDefault();
+            ?.FirstOrDefault();
 
         if (download is null)
         {

code/backend/Cleanuparr.Infrastructure/Features/DownloadClient/QBittorrent/QBittorrentClientWrapper.cs

@@ -20,7 +20,7 @@ public sealed class QBittorrentClientWrapper : IQBittorrentClientWrapper
     public Task<ApiVersion> GetApiVersionAsync()
         => _client.GetApiVersionAsync();
 
-    public Task<IReadOnlyList<TorrentInfo>> GetTorrentListAsync(TorrentListQuery query)
+    public Task<IReadOnlyList<TorrentInfo>?> GetTorrentListAsync(TorrentListQuery query)
         => _client.GetTorrentListAsync(query);
 
     public Task<TorrentProperties?> GetTorrentPropertiesAsync(string hash)