Fix race condition on startup and improve fault tolerance

src/UniGetUI.Avalonia/Infrastructure/AvaloniaAppHost.cs

@@ -1,5 +1,6 @@
 using System.Runtime.InteropServices;
 using Avalonia;
+using Avalonia.Threading;
 using UniGetUI.Core.Data;
 using UniGetUI.Core.Logging;
 using UniGetUI.Core.Tools;
@@ -68,6 +69,11 @@ Welcome to UniGetUI Version {CoreData.VersionName}
         Logger.ImportantInfo($"Packaged (MSIX): {CoreTools.IsPackagedApp()}");
         Logger.ImportantInfo($"Args: {(args.Length > 0 ? string.Join(" ", args) : "(none)")}");
 
+        // Bind Avalonia's UI-thread dispatcher to this (main/STA) thread before the single-instance
+        // listener starts: if a second instance connects mid-startup, the listener's Dispatcher.UIThread.Post
+        // would otherwise bind it to the worker thread and make Win32Platform.Initialize throw.
+        _ = Dispatcher.UIThread;
+
         if (!TryRegisterSingleInstance(args))
         {
             return;

src/UniGetUI.PackageEngine.PackageEngine/PEInterface.cs

@@ -33,57 +33,85 @@ public static class PEInterface
     {
         private const int ManagerLoadTimeout = 60; // 60 seconds timeout for Package Manager initialization (in seconds)
 #if WINDOWS
-        public static readonly WinGet WinGet = new();
-        public static readonly Scoop Scoop = new();
-        public static readonly Chocolatey Chocolatey = new();
+        public static readonly WinGet? WinGet = Create(() => new WinGet());
+        public static readonly Scoop? Scoop = Create(() => new Scoop());
+        public static readonly Chocolatey? Chocolatey = Create(() => new Chocolatey());
 #endif
-        public static readonly Npm Npm = new();
-        public static readonly Bun Bun = new();
-        public static readonly Pip Pip = new();
-        public static readonly DotNet DotNet = new();
-        public static readonly PowerShell7 PowerShell7 = new();
+        public static readonly Npm? Npm = Create(() => new Npm());
+        public static readonly Bun? Bun = Create(() => new Bun());
+        public static readonly Pip? Pip = Create(() => new Pip());
+        public static readonly DotNet? DotNet = Create(() => new DotNet());
+        public static readonly PowerShell7? PowerShell7 = Create(() => new PowerShell7());
 #if WINDOWS
-        public static readonly PowerShell PowerShell = new();
+        public static readonly PowerShell? PowerShell = Create(() => new PowerShell());
 #endif
-        public static readonly Cargo Cargo = new();
-        public static readonly Vcpkg Vcpkg = new();
+        public static readonly Cargo? Cargo = Create(() => new Cargo());
+        public static readonly Vcpkg? Vcpkg = Create(() => new Vcpkg());
 #if !WINDOWS
-        public static readonly Apt Apt = new();
-        public static readonly Dnf Dnf = new();
-        public static readonly Pacman Pacman = new();
-        public static readonly Homebrew Homebrew = new();
-        public static readonly Snap Snap = new();
-        public static readonly Flatpak Flatpak = new();
+        public static readonly Apt? Apt = Create(() => new Apt());
+        public static readonly Dnf? Dnf = Create(() => new Dnf());
+        public static readonly Pacman? Pacman = Create(() => new Pacman());
+        public static readonly Homebrew? Homebrew = Create(() => new Homebrew());
+        public static readonly Snap? Snap = Create(() => new Snap());
+        public static readonly Flatpak? Flatpak = Create(() => new Flatpak());
 #endif
 
         public static readonly IPackageManager[] Managers = CreateManagers();
 
+        // A single manager that fails to construct must not take down the whole engine (and with it
+        // the app, via TypeInitializationException). Log it and leave the field null; CreateManagers
+        // drops nulls so the rest of the managers stay usable.
+        private static T? Create<T>(Func<T> factory) where T : class, IPackageManager
+        {
+            try
+            {
+                return factory();
+            }
+            catch (Exception ex)
+            {
+                // Logging runs inside its own guard: this method must never throw, or it would
+                // re-trigger the TypeInitializationException it exists to prevent (it runs from
+                // a static field initializer).
+                try
+                {
+                    Logger.Error($"Failed to construct package manager {typeof(T).Name}; it will be unavailable this session.");
+                    Logger.Error(ex);
+                }
+                catch { /* swallow: never let static initialization fail */ }
+                return null;
+            }
+        }
+
         private static IPackageManager[] CreateManagers()
         {
-            List<IPackageManager> managers = [Npm, Bun, Pip, Cargo, Vcpkg, DotNet, PowerShell7];
+            List<IPackageManager?> candidates = [Npm, Bun, Pip, Cargo, Vcpkg, DotNet, PowerShell7];
 #if WINDOWS
-            managers.InsertRange(0, [WinGet, Scoop, Chocolatey]);
-            managers.Add(PowerShell);
+            candidates.InsertRange(0, [WinGet, Scoop, Chocolatey]);
+            candidates.Add(PowerShell);
 #else
-            managers.Insert(0, Homebrew);
+            candidates.Insert(0, Homebrew);
             if (OperatingSystem.IsLinux())
             {
                 var families = ReadLinuxDistroFamilies();
                 // If /etc/os-release is unreadable, include both as a safe fallback.
                 bool unknown = families.Count == 0;
                 if (unknown || families.Contains("debian") || families.Contains("ubuntu"))
-                    managers.Add(Apt);
+                    candidates.Add(Apt);
                 if (unknown || families.Contains("fedora") || families.Contains("rhel") || families.Contains("centos"))
-                    managers.Add(Dnf);
+                    candidates.Add(Dnf);
                 if (unknown || families.Contains("arch"))
-                    managers.Add(Pacman);
+                    candidates.Add(Pacman);
                 if (unknown || families.Contains("ubuntu") || families.Contains("debian") || families.Contains("fedora") || families.Contains("arch"))
                 {
-                    managers.Add(Snap);
-                    managers.Add(Flatpak);
+                    candidates.Add(Snap);
+                    candidates.Add(Flatpak);
                 }
             }
 #endif
+            List<IPackageManager> managers = [];
+            foreach (IPackageManager? manager in candidates)
+                if (manager is not null)
+                    managers.Add(manager);
             return [.. managers];
         }
 

src/UniGetUI/CrashHandler.cs

@@ -182,6 +182,8 @@ static string GetExceptionData(Exception e)
                     {{e.StackTrace?.Replace("\n", "\n        ")}}
             """;
 
+        Exception originalException = e;
+
         try
         {
             int i = 0;
@@ -216,6 +218,19 @@ Inner exception details (depth level: {{i}})
             // ignore
         }
 
+        // Authoritative fallback: ToString() recurses through every inner exception (and all of an
+        // AggregateException's inners) with their stack traces. The walk above only follows the single
+        // .InnerException chain, so it can drop the real cause of e.g. a TypeInitializationException.
+        try
+        {
+            Error_String += "\n\n\n———————————————————————————————————————————————————————————\n"
+                + "Full exception detail (ToString):\n" + originalException;
+        }
+        catch
+        {
+            // ignore
+        }
+
         Error_String = Logger.Redact(Error_String);
 
         Console.WriteLine(Error_String);

src/UniGetUI/Pages/DialogPages/IgnoredUpdates.xaml.cs

@@ -44,12 +44,15 @@ private void UpdateData()
 
             foreach (var (ignoredId, version) in rawIgnoredPackages)
             {
-                IPackageManager manager = PEInterface.WinGet; // Manager by default
+                IPackageManager? manager = PEInterface.WinGet; // Manager by default
                 if (ManagerNameReference.ContainsKey(ignoredId.Split("\\")[0]))
                 {
                     manager = ManagerNameReference[ignoredId.Split("\\")[0]];
                 }
 
+                if (manager is null)
+                    continue;
+
                 ignoredPackages.Add(
                     new IgnoredPackageEntry(
                         ignoredId.Split("\\")[^1],

src/UniGetUI/Pages/MainView.xaml.cs

@@ -175,7 +175,7 @@ public MainView(AutoSuggestBox mainTextBlock)
             }
 
             if (
-                !PEInterface.Chocolatey.Status.Found
+                PEInterface.Chocolatey is { Status.Found: false }
                 && Chocolatey.HasLegacyBundledInstallation()
                 && !Settings.Get(Settings.K.AlreadyWarnedAboutChocolateyMigration)
             )

src/UniGetUI/Pages/SettingsPages/ManagersPages/PackageManager.xaml.cs

@@ -85,6 +85,10 @@ protected override void OnNavigatedTo(NavigationEventArgs e)
             else
                 throw new InvalidCastException("The specified type was not a package manager!");
 
+            // The manager failed to construct at startup (see PEInterface): there is nothing to configure.
+            if (Manager is null)
+                return;
+
             ReapplyProperties?.Invoke(this, new());
 
             ApplyManagerState();