WindowServer: Add sanity checks to `create_window` IPC

Userland/Services/WindowServer/ClientConnection.cpp

@@ -465,6 +465,11 @@ Messages::WindowServer::CreateWindowResponse ClientConnection::create_window(Gfx
         }
     }
 
+    if (type < 0 || type >= (i32)WindowType::_Count) {
+        did_misbehave("CreateWindow with a bad type");
+        return nullptr;
+    }
+
     int window_id = m_next_window_id++;
     auto window = Window::construct(*this, (WindowType)type, window_id, modal, minimizable, frameless, resizable, fullscreen, accessory, parent_window);
 
@@ -492,7 +497,8 @@ Messages::WindowServer::CreateWindowResponse ClientConnection::create_window(Gfx
     window->set_alpha_hit_threshold(alpha_hit_threshold);
     window->set_size_increment(size_increment);
     window->set_base_size(base_size);
-    window->set_resize_aspect_ratio(resize_aspect_ratio);
+    if (resize_aspect_ratio.has_value() && !resize_aspect_ratio.value().is_null())
+        window->set_resize_aspect_ratio(resize_aspect_ratio);
     window->invalidate(true, true);
     if (window->type() == WindowType::Applet)
         AppletManager::the().add_applet(*window);

Userland/Services/WindowServer/Window.cpp

@@ -208,7 +208,8 @@ void Window::nudge_into_desktop(bool force_titlebar_visible)
 
 void Window::set_minimum_size(const Gfx::IntSize& size)
 {
-    VERIFY(!size.is_empty());
+    if (size.is_null())
+        return;
 
     if (m_minimum_size == size)
         return;

Userland/Services/WindowServer/WindowType.h

@@ -20,6 +20,7 @@ enum class WindowType {
     Desktop,
     ToolWindow,
     AppletArea,
+    _Count
 };
 
 }