Provide more context in exception messages

DiscordChatExporter.Cli.Tests/Infra/ExportWrapper.cs

@@ -105,7 +105,7 @@ public static class ExportWrapper
         if (message is null)
         {
             throw new InvalidOperationException(
-                $"Message '{messageId}' does not exist in the export of channel '{channelId}'."
+                $"Message #{messageId} does not exist in the export of channel #{channelId}."
             );
         }
 
@@ -129,7 +129,7 @@ public static class ExportWrapper
         if (message.ValueKind == JsonValueKind.Undefined)
         {
             throw new InvalidOperationException(
-                $"Message '{messageId}' does not exist in the export of channel '{channelId}'."
+                $"Message #{messageId} does not exist in the export of channel #{channelId}."
             );
         }
 

DiscordChatExporter.Cli/Commands/Base/ExportCommandBase.cs

@@ -168,7 +168,9 @@ public abstract class ExportCommandBase : DiscordCommandBase
         {
             throw new CommandException(
                 "Attempted to export multiple channels, but the output path is neither a directory nor a template. "
-                    + "If the provided output path is meant to be treated as a directory, make sure it ends with a slash."
+                    + "If the provided output path is meant to be treated as a directory, make sure it ends with a slash. "
+                    + "Provided output path: "
+                    + OutputPath
             );
         }
 

DiscordChatExporter.Core/Exceptions/DiscordChatExporterException.cs

@@ -6,8 +6,8 @@ public class DiscordChatExporterException : Exception
 {
     public bool IsFatal { get; }
 
-    public DiscordChatExporterException(string message, bool isFatal = false)
+    public DiscordChatExporterException(string message, bool isFatal = false, Exception? innerException = null)
-        : base(message)
+        : base(message, innerException)
     {
         IsFatal = isFatal;
     }

DiscordChatExporter.Core/Exporting/ChannelExporter.cs

@@ -22,7 +22,7 @@ public class ChannelExporter(DiscordClient discord)
         if (request.Channel.Kind == ChannelKind.GuildForum)
         {
             throw new DiscordChatExporterException(
-                "Channel is a forum and cannot be exported directly. "
+                $"Channel '{request.Channel.Name}' (#{request.Channel.Id}) is a forum and cannot be exported directly. "
                     + "You need to pull its threads and export them individually."
             );
         }
@@ -30,14 +30,16 @@ public class ChannelExporter(DiscordClient discord)
         // Check if the channel is empty
         if (request.Channel.IsEmpty)
         {
-            throw new DiscordChatExporterException("Channel does not contain any messages.");
+            throw new DiscordChatExporterException(
+                $"Channel '{request.Channel.Name}' (#{request.Channel.Id}) does not contain any messages."
+            );
         }
 
         // Check if the 'after' boundary is valid
         if (request.After is not null && !request.Channel.MayHaveMessagesAfter(request.After.Value))
         {
             throw new DiscordChatExporterException(
-                "Channel does not contain any messages within the specified period."
+                $"Channel '{request.Channel.Name}' (#{request.Channel.Id}) does not contain any messages within the specified period."
             );
         }
 
@@ -48,7 +50,7 @@ public class ChannelExporter(DiscordClient discord)
         )
         {
             throw new DiscordChatExporterException(
-                "Channel does not contain any messages within the specified period."
+                $"Channel '{request.Channel.Name}' (#{request.Channel.Id}) does not contain any messages within the specified period."
             );
         }
 
@@ -67,6 +69,8 @@ public class ChannelExporter(DiscordClient discord)
                 cancellationToken
             )
         )
+        {
+            try
             {
                 // Resolve members for referenced users
                 foreach (var user in message.GetReferencedUsers())
@@ -76,12 +80,22 @@ public class ChannelExporter(DiscordClient discord)
                 if (request.MessageFilter.IsMatch(message))
                     await messageExporter.ExportMessageAsync(message, cancellationToken);
             }
+            catch (Exception ex)
+            {
+                // Provide more context to the exception, to simplify debugging based on error messages
+                throw new DiscordChatExporterException(
+                    $"Failed to export message #{message.Id} in channel '{request.Channel.Name}' (#{request.Channel.Id}).",
+                    ex is not DiscordChatExporterException dex || dex.IsFatal,
+                    ex
+                );
+            }
+        }
 
         // Throw if no messages were exported
         if (messageExporter.MessagesExported <= 0)
         {
             throw new DiscordChatExporterException(
-                "Channel does not contain any matching messages within the specified period."
+                $"Channel '{request.Channel.Name}' (#{request.Channel.Id}) does not contain any matching messages within the specified period."
             );
         }
     }

DiscordChatExporter.Gui/ViewModels/Components/DashboardViewModel.cs

@@ -277,9 +277,7 @@ public class DashboardViewModel : PropertyChangedBase
                     }
                     catch (DiscordChatExporterException ex) when (!ex.IsFatal)
                     {
-                        _eventAggregator.Publish(
+                        _eventAggregator.Publish(new NotificationMessage(ex.Message.TrimEnd('.')));
-                            new NotificationMessage(ex.Message.TrimEnd('.') + $" ({channel.Name})")
-                        );
                     }
                     finally
                     {