Proposal for how to fix #11114

src/cascadia/TerminalApp/AppActionHandlers.cpp

@@ -173,6 +173,15 @@ namespace winrt::TerminalApp::implementation
         }
         else if (const auto& realArgs = args.ActionArgs().try_as<SplitPaneArgs>())
         {
+            if (const auto index = newTerminalArgs.ProfileIndex())
+            {
+                if (index >= _settings->ActiveProfiles().Size())
+                {
+                    args.Handled(false);
+                    return;
+                }
+            }
+
             _SplitPane(realArgs.SplitDirection(),
                        realArgs.SplitMode(),
                        // This is safe, we're already filtering so the value is (0, 1)
@@ -290,6 +299,15 @@ namespace winrt::TerminalApp::implementation
         }
         else if (const auto& realArgs = args.ActionArgs().try_as<NewTabArgs>())
         {
+            if (const auto index = newTerminalArgs.ProfileIndex())
+            {
+                if (index >= _settings->ActiveProfiles().Size())
+                {
+                    args.Handled(false);
+                    return;
+                }
+            }
+
             LOG_IF_FAILED(_OpenNewTab(realArgs.TerminalArgs()));
             args.Handled(true);
         }

src/cascadia/TerminalApp/TabManagement.cpp

@@ -63,6 +63,12 @@ namespace winrt::TerminalApp::implementation
     try
     {
         const auto profile{ _settings.GetProfileForArgs(newTerminalArgs) };
+        // GH#11114: GetProfileForArgs can return null if the index is higher
+        // than the number of available profiles.
+        if (!profile)
+        {
+            return S_FALSE;
+        }
         const auto settings{ TerminalSettings::CreateWithNewTerminalArgs(_settings, newTerminalArgs, *_bindings) };
 
         _CreateNewTabWithProfileAndSettings(profile, settings, existingConnection);

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -1560,6 +1560,12 @@ namespace winrt::TerminalApp::implementation
             if (!profile)
             {
                 profile = _settings.GetProfileForArgs(newTerminalArgs);
+                // GH#11114: GetProfileForArgs can return null if the index is
+                // higher than the number of available profiles.
+                if (!profile)
+                {
+                    return;
+                }
                 controlSettings = TerminalSettings::CreateWithNewTerminalArgs(_settings, newTerminalArgs, *_bindings);
             }
 

src/cascadia/TerminalSettingsModel/CascadiaSettings.cpp

@@ -537,6 +537,13 @@ Model::Profile CascadiaSettings::GetProfileForArgs(const Model::NewTerminalArgs&
             {
                 return profile;
             }
+            else
+            {
+                // GH#11114 - Return NOTHING if they asked for a profile index
+                // outside the range of available profiles.
+                // Really, the caller should check this beforehand
+                return nullptr;
+            }
         }
     }