fix: Only show server error when we have one

Leaving the server error box around was confusing users. There's no
reason to leave it around if things are working now.

Fixes #419

Author: qdot

Buttplug.Apps.ServerGUI/ServerControl.xaml

@@ -1,4 +1,4 @@
-<UserControl x:Class="Buttplug.Apps.ServerGUI.ServerControl"
+<UserControl x:Class="Buttplug.Apps.ServerGUI.ServerControl"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
@@ -48,7 +48,7 @@
                 <Label Name="ConnStatus" Content="(Not Connected)" Grid.Row="2" HorizontalAlignment="Left" Margin="72,4,0,0" VerticalAlignment="Top"/>
                 <Button Name="DisconnectButton"  Height="25" Grid.Row="2" Content="Disconnect" IsEnabled="False" HorizontalAlignment="Right" Margin="0,5,0,0" VerticalAlignment="Top" Width="75" Click="DisconnectButton_Click"/>
 
-                <Label Content="Last Error:"  Grid.Row="3" HorizontalAlignment="Left" Margin="0,5,0,0" VerticalAlignment="Top"/>
+                <Label Name="LastErrorLabel"  Content="Error:"  Grid.Row="3" HorizontalAlignment="Left" Margin="0,5,0,0" VerticalAlignment="Top" Visibility="Hidden"/>
                 <TextBlock Name="LastError" Text="" Grid.Row="3" HorizontalAlignment="Left" Margin="65,10,0,0" VerticalAlignment="Top" TextWrapping="Wrap"/>
             </Grid>
         </GroupBox>

Buttplug.Apps.ServerGUI/ServerControl.xaml.cs

@@ -89,6 +89,20 @@ public ServerControl(IButtplugServerFactory bpFactory)
             _log.OnLogException += ExceptionLogged;
         }
 
+        private void SetLastError(string aErrorMsg)
+        {
+            LastErrorLabel.Visibility = Visibility.Visible;
+            LastError.Visibility = Visibility.Visible;
+            LastError.Text = aErrorMsg;
+        }
+
+        private void ClearLastError()
+        {
+            LastErrorLabel.Visibility = Visibility.Hidden;
+            LastError.Visibility = Visibility.Hidden;
+            LastError.Text = string.Empty;
+        }
+
         private void WebSocketExceptionHandler(object aObj, [NotNull] UnhandledExceptionEventArgs aEx)
         {
             _toastTimer.Enabled = true;
@@ -120,6 +134,8 @@ private void WebSocketConnectionAccepted(object aObj, [NotNull] ConnectionEventA
             {
                 ConnStatus.Content = "(Connected) " + aEvent.ClientName;
                 DisconnectButton.IsEnabled = true;
+                // We've gotten a connection, clear the last error.
+                ClearLastError();
             });
         }
 
@@ -162,7 +178,7 @@ private void ExceptionLogged(object aObj, [NotNull] LogExceptionEventArgs aEvent
                 Dispatcher.InvokeAsync(() =>
                 {
                     // Show the error message in the app
-                    LastError.Text = aEvent.ErrorMessage;
+                    SetLastError(aEvent.ErrorMessage);
                 });
                 _toastTimer.Enabled = true;
             }
@@ -203,6 +219,9 @@ public void StartServer()
                 ConnStatus.Content = "(Not Connected)";
                 DisconnectButton.IsEnabled = false;
                 ConnInfo.IsEnabled = true;
+
+                // We've brought the server up, clear the error.
+                ClearLastError();
             }
             catch (SocketException e)
             {