feat: Fixed a possible null reference exception.

src/ZonyLrcTools.Cli/Commands/SubCommand/DownloadCommand.cs

@@ -103,7 +103,9 @@ namespace ZonyLrcTools.Cli.Commands.SubCommand
 
             var warpTask = new WarpTask(ParallelNumber);
             var warpTaskList = files.Select(file => warpTask.RunAsync(() => Task.Run(async () => await _tagLoader.LoadTagAsync(file))));
-            var result = (await Task.WhenAll(warpTaskList)).Where(m => !string.IsNullOrEmpty(m.Name) || !string.IsNullOrEmpty(m.Artist));
+            var result = (await Task.WhenAll(warpTaskList))
+                .Where(m => m != null)
+                .Where(m => !string.IsNullOrEmpty(m.Name) || !string.IsNullOrEmpty(m.Artist));
 
             _logger.LogInformation($"已成功加载 {files.Count} 个音乐文件的标签信息。");
 

src/ZonyLrcTools.Cli/Infrastructure/Tag/DefaultTagLoader.cs

@@ -1,6 +1,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using ZonyLrcTools.Cli.Config;
 using ZonyLrcTools.Cli.Infrastructure.DependencyInject;
@@ -15,14 +16,18 @@ namespace ZonyLrcTools.Cli.Infrastructure.Tag
     {
         protected readonly IEnumerable<ITagInfoProvider> TagInfoProviders;
         protected readonly IBlockWordDictionary BlockWordDictionary;
+        protected readonly ILogger<DefaultTagLoader> _logger;
+
         protected ToolOptions Options;
 
         public DefaultTagLoader(IEnumerable<ITagInfoProvider> tagInfoProviders,
             IBlockWordDictionary blockWordDictionary,
-            IOptions<ToolOptions> options)
+            IOptions<ToolOptions> options,
+            ILogger<DefaultTagLoader> logger)
         {
             TagInfoProviders = tagInfoProviders;
             BlockWordDictionary = blockWordDictionary;
+            _logger = logger;
             Options = options.Value;
         }
 
@@ -43,6 +48,8 @@ namespace ZonyLrcTools.Cli.Infrastructure.Tag
                 }
             }
 
+            _logger.LogWarning($"{filePath} 没有找到正确的标签信息，请考虑调整正则表达式。");
+
             return null;
         }