Fix file lock not getting disposed when postamble throws an exception

DiscordChatExporter.Cli.Tests/Fixtures/ExportWrapperFixture.cs

@@ -33,6 +33,8 @@ public class ExportWrapperFixture : IDisposable
 
         // Perform export only if it hasn't been done before
         if (!File.Exists(filePath))
+        {
+            try
             {
                 await new ExportChannelsCommand
                 {
@@ -42,6 +44,13 @@ public class ExportWrapperFixture : IDisposable
                     OutputPath = filePath
                 }.ExecuteAsync(new FakeConsole());
             }
+            catch
+            {
+                // If the export fails, delete the file to prevent it from being used by tests
+                File.Delete(filePath);
+                throw;
+            }
+        }
 
         return await File.ReadAllTextAsync(filePath);
     }

DiscordChatExporter.Core/Exporting/MessageExporter.cs

@@ -22,12 +22,19 @@ internal partial class MessageExporter : IAsyncDisposable
     private async ValueTask ResetWriterAsync(CancellationToken cancellationToken = default)
     {
         if (_writer is not null)
+        {
+            try
             {
                 await _writer.WritePostambleAsync(cancellationToken);
+            }
+            // Writer must be disposed, even if writing postamble fails
+            finally
+            {
                 await _writer.DisposeAsync();
                 _writer = null;
             }
         }
+    }
 
     private async ValueTask<MessageWriter> GetWriterAsync(CancellationToken cancellationToken = default)
     {

DiscordChatExporter.Core/Exporting/Writers/HtmlMessageWriter.cs

@@ -67,9 +67,7 @@ internal class HtmlMessageWriter : MessageWriter
     }
 
     // Use <!--wmm:ignore--> to preserve blocks of code inside the templates
-    private string Minify(string html) => _minifier
-        .Minify(html, false)
-        .MinifiedContent;
+    private string Minify(string html) => _minifier.Minify(html, false).MinifiedContent;
 
     public override async ValueTask WritePreambleAsync(
         CancellationToken cancellationToken = default)