Fixed: Handle response when magnet is empty

Fixes #404

src/Prowlarr.Api.V1/Indexers/NewznabController.cs

@@ -129,11 +129,11 @@ namespace NzbDrone.Api.V1.Indexers
 
                     foreach (var result in results.Releases)
                     {
-                        result.DownloadUrl = result.DownloadUrl != null ? _downloadMappingService.ConvertToProxyLink(new Uri(result.DownloadUrl), request.server, indexerDef.Id, result.Title).ToString() : null;
+                        result.DownloadUrl = result.DownloadUrl.IsNotNullOrWhiteSpace() ? _downloadMappingService.ConvertToProxyLink(new Uri(result.DownloadUrl), request.server, indexerDef.Id, result.Title).ToString() : null;
 
                         if (result.DownloadProtocol == DownloadProtocol.Torrent)
                         {
-                            ((TorrentInfo)result).MagnetUrl = ((TorrentInfo)result).MagnetUrl != null ? _downloadMappingService.ConvertToProxyLink(new Uri(((TorrentInfo)result).MagnetUrl), request.server, indexerDef.Id, result.Title).ToString() : null;
+                            ((TorrentInfo)result).MagnetUrl = ((TorrentInfo)result).MagnetUrl.IsNotNullOrWhiteSpace() ? _downloadMappingService.ConvertToProxyLink(new Uri(((TorrentInfo)result).MagnetUrl), request.server, indexerDef.Id, result.Title).ToString() : null;
                         }
                     }
 

src/Prowlarr.Api.V1/Search/SearchController.cs

@@ -127,8 +127,8 @@ namespace Prowlarr.Api.V1.Search
                 var release = downloadDecision.ToResource();
 
                 _remoteReleaseCache.Set(GetCacheKey(release), downloadDecision, TimeSpan.FromMinutes(30));
-                release.DownloadUrl = release.DownloadUrl != null ? _downloadMappingService.ConvertToProxyLink(new Uri(release.DownloadUrl), serverUrl, release.IndexerId, release.Title).ToString() : null;
+                release.DownloadUrl = release.DownloadUrl.IsNotNullOrWhiteSpace() ? _downloadMappingService.ConvertToProxyLink(new Uri(release.DownloadUrl), serverUrl, release.IndexerId, release.Title).ToString() : null;
-                release.MagnetUrl = release.MagnetUrl != null ? _downloadMappingService.ConvertToProxyLink(new Uri(release.MagnetUrl), serverUrl, release.IndexerId, release.Title).ToString() : null;
+                release.MagnetUrl = release.MagnetUrl.IsNotNullOrWhiteSpace() ? _downloadMappingService.ConvertToProxyLink(new Uri(release.MagnetUrl), serverUrl, release.IndexerId, release.Title).ToString() : null;
 
                 result.Add(release);
             }