WindowServer: Assert that a window is not being set as empty

Author: https://github.com/shannonbooth
Commit: https://github.com/SerenityOS/serenity/commit/cef3988e301
Pull-request: https://github.com/SerenityOS/serenity/pull/1209
Reviewed-by: https://github.com/awesomekling

Servers/WindowServer/Window.cpp

@@ -96,6 +96,7 @@ void Window::set_title(const String& title)
 
 void Window::set_rect(const Gfx::Rect& rect)
 {
+    ASSERT(!rect.is_empty());
     Gfx::Rect old_rect;
     if (m_rect == rect)
         return;

Servers/WindowServer/Window.h

@@ -142,6 +142,7 @@ public:
     void set_rect(int x, int y, int width, int height) { set_rect({ x, y, width, height }); }
     void set_rect_without_repaint(const Gfx::Rect& rect)
     {
+        ASSERT(!rect.is_empty());
         if (m_rect == rect)
             return;
         auto old_rect = m_rect;