fix: two small fixes to crash causing bugs

core/src/ecs/world.cpp

@@ -806,13 +806,20 @@ auto World::Components::remove(const reflection::Type& type) -> Components&
         return *this;
     }
 
-    // Trigger any observers that are interested in this change.
+    // Trigger any observers that are interested in this change, before component is removed.
     CommandBuffer cmdBuffer{mWorld};
     if (mWorld.mObservers->notifyRemove(cmdBuffer, mEntity, columnId))
     {
         cmdBuffer.commit();
     }
 
+    // Update old archetype since observers might have modified it.
+    oldArchetype = mWorld.mEntityPool.archetype(mEntity.index);
+    if (!mWorld.mArchetypeGraph.contains(oldArchetype, columnId))
+    {
+        return *this;
+    }
+
     auto& oldTable = mWorld.mTables.dense().at(oldArchetype);
 
     // Otherwise, we'll need to move the entity to a new archetype.

core/tests/ecs/world.cpp

@@ -2,6 +2,7 @@
 
 #include <doctest/doctest.h>
 
+#include <cubos/core/ecs/observer/observers.hpp>
 #include <cubos/core/ecs/world.hpp>
 #include <cubos/core/reflection/external/primitives.hpp>
 #include <cubos/core/reflection/type.hpp>
@@ -547,5 +548,38 @@ TEST_CASE("ecs::World")
             CHECK(it->type->is<IntegerRelation>());
         }
     }
+
+    SUBCASE("world remove works correctly with remove observers")
+    {
+        auto foo = world.create();
+        auto bar = world.create();
+
+        world.components(foo).add(IntegerComponent{0});
+        auto columnId = cubos::core::ecs::ColumnId::make(world.types().id<IntegerComponent>());
+        world.observers().hookOnRemove(columnId, cubos::core::ecs::System<void>::make(world, [foo, bar](World& w) {
+                                           w.components(foo).add(ParentComponent{bar});
+                                       }));
+        // Removing IntegerComponent triggers observer, which alters the entity
+        world.components(foo).remove<IntegerComponent>();
+        CHECK_FALSE(world.components(foo).has<IntegerComponent>());
+        CHECK(world.components(foo).has<ParentComponent>());
+    }
+
+    SUBCASE("world destroy works correctly with remove observers")
+    {
+        auto foo = world.create();
+        auto bar = world.create();
+
+        world.components(foo).add(IntegerComponent{0});
+        auto columnId = cubos::core::ecs::ColumnId::make(world.types().id<IntegerComponent>());
+        world.observers().hookOnRemove(columnId, cubos::core::ecs::System<void>::make(world, [foo, bar](World& w) {
+                                           w.components(foo).add(ParentComponent{bar});
+                                           w.components(bar).add(ParentComponent{foo});
+                                       }));
+        // Destroying foo triggers observer, which alters the entity
+        world.destroy(foo);
+        CHECK_FALSE(world.isAlive(foo));
+        CHECK(world.components(bar).has<ParentComponent>());
+    }
 }
 // NOLINTEND(readability-function-size)

engine/src/tools/play_pause/plugin.cpp

@@ -54,9 +54,8 @@ void cubos::engine::playPauseToolPlugin(Cubos& cubos)
             {
                 state.scale = 1.0F;
             }
-
-            ImGui::End();
         }
+        ImGui::End();
 
         if (!state.paused)
         {