Fix OpenRCT2#21748: TileElement out of bounds

This fixes crashes observed and allows the park to load. The park is
overlarge and breaks some assumptions we have in our code.

distribution/changelog.txt

@@ -1,5 +1,6 @@
 0.4.11 (in development)
 ------------------------------------------------------------------------
+- Fix: [#21749] Crash when loading park bigger than current limits.
 
 0.4.10 (2024-04-02)
 ------------------------------------------------------------------------

src/openrct2/world/Map.cpp

@@ -301,7 +301,14 @@ int32_t TileElementIteratorNext(TileElementIterator* it)
     if (it->element == nullptr)
     {
         it->element = MapGetFirstElementAt(TileCoordsXY{ it->x, it->y });
-        return 1;
+        if (it->element == nullptr)
+        {
+            return 0;
+        }
+        else
+        {
+            return 1;
+        }
     }
 
     if (!it->element->IsLastForTile())
@@ -315,15 +322,29 @@ int32_t TileElementIteratorNext(TileElementIterator* it)
     {
         it->y++;
         it->element = MapGetFirstElementAt(TileCoordsXY{ it->x, it->y });
-        return 1;
+        if (it->element == nullptr)
+        {
+            return 0;
+        }
+        else
+        {
+            return 1;
+        }
     }
 
     if (it->x < (gameState.MapSize.x - 2))
     {
         it->y = 1;
         it->x++;
         it->element = MapGetFirstElementAt(TileCoordsXY{ it->x, it->y });
-        return 1;
+        if (it->element == nullptr)
+        {
+            return 0;
+        }
+        else
+        {
+            return 1;
+        }
     }
 
     return 0;

src/openrct2/world/MapAnimation.cpp

@@ -619,6 +619,10 @@ void MapAnimationAutoCreate()
 
 void MapAnimationAutoCreateAtTileElement(TileCoordsXY coords, TileElement* el)
 {
+    if (el == nullptr)
+    {
+        return;
+    }
     auto loc = CoordsXYZ{ coords.ToCoordsXY(), el->GetBaseZ() };
     switch (el->GetType())
     {