Plugins: Fail gracefully on multiple instances of same plugin

Il2CppInspector.CLI/PluginOptions.cs

@@ -121,6 +121,7 @@ namespace Il2CppInspector.CLI
         // Get plugin option classes
         public static Type[] GetPluginOptionTypes() {
             // Don't do anything if there are no loaded plugins
+            try {
                 var plugins = PluginManager.AvailablePlugins;
 
                 if (!plugins.Any())
@@ -129,6 +130,13 @@ namespace Il2CppInspector.CLI
                 // Create CommandLine-friendly option classes for each plugin
                 return plugins.Select(p => CreateOptionsFromPlugin(p)).ToArray();
             }
+            catch (InvalidOperationException ex) {
+                Console.Error.WriteLine(ex.Message);
+                Environment.Exit(1);
+
+                return null;
+            }
+        }
 
         // Parse all options for all plugins
         public static bool ParsePluginOptions(IEnumerable<string> pluginOptions, Type[] optionsTypes) {

Il2CppInspector.Common/Plugins/Internal/PluginManager.cs

@@ -174,6 +174,11 @@ namespace Il2CppInspector
                         // Current version
                         if (typeof(IPlugin).IsAssignableFrom(type) && !type.IsAbstract) {
                             var plugin = (IPlugin) Activator.CreateInstance(type);
+
+                            // Don't allow multiple identical plugins to load
+                            if (AsInstance.ManagedPlugins.Any(p => p.Plugin.Id == plugin.Id))
+                                throw new Exception($"Multiple copies of {plugin.Name} were found. Please ensure the plugins folder only contains one copy of each plugin.");
+
                             AsInstance.ManagedPlugins.Add(new ManagedPlugin { Plugin = plugin, Available = true, Enabled = false });
                         }
 

Il2CppInspector.GUI/App.xaml.cs

@@ -126,7 +126,12 @@ namespace Il2CppInspectorGUI
             catch (NotSupportedException) { }
 
             // Load plugins if they aren't already
+            try {
                 PluginManager.EnsureInit();
+            } catch (InvalidOperationException ex) {
+                MessageBox.Show(ex.Message, "Fatal error loading plugins");
+                Environment.Exit(1);
+            }
 
             // Arrange plugins
             var loadedPlugins = PluginManager.AsInstance.ManagedPlugins;