Assign ActiveWindowID to NullWindowID if window doesn't exist, misc

src/text_editor/text_editor.cpp

@@ -603,11 +603,17 @@ void Update(Event event) {
             }
         }
 
+        {
             ActiveWindowID = NextActiveWindowID;
             Window *window = GetWindow(ActiveWindowID, NULL);
             if (window == NULL || window->visible == false) {
                 ActiveWindowID = NextActiveWindowID = LastActiveLayoutWindowID;
-            window = GetWindow(ActiveWindowID);
+                window = GetWindow(ActiveWindowID, NULL);
+                if (window == NULL) {
+                    ActiveWindowID = NullWindowID;
+                    Assert(GetWindow(ActiveWindowID, NULL));
+                }
+            }
         }
 
         // Behavior where these windows cannot be visible at the same time
@@ -625,6 +631,7 @@ void Update(Event event) {
         }
 
         if (ActiveWindowID != LastActiveLayoutWindowID) {
+            Window *window = GetWindow(ActiveWindowID, NULL);
             if (window->layout) {
                 LastActiveLayoutWindowID = ActiveWindowID;
             }

src/text_editor/window.cpp

@@ -26,15 +26,13 @@ Window *GetWindow(WindowID id, Window *default_window = Windows[0]) {
 }
 
 void Close(WindowID id) {
-    Window *window = GetWindow(id, NULL);
+    Window *window = GetWindow(id);
-    if (window) {
     if (window->id.id == 0) {
         return;
     }
     window->close = true;
     RunGCThisFrame = true;
 }
-}
 
 Window *FindWindow(ViewID view_id, Window *default_window = NULL) {
     For(Windows) {