Merge pull request rails#50353 from lucasmazza/lm/fix-load-async-null-relation

Fix `load_async` for null relations

Author: byroot

activerecord/lib/active_record/relation.rb

@@ -960,7 +960,7 @@ def exec_queries(&block)
       def exec_main_query(async: false)
         if @none
           if async
-            return Promise::Complete.new([])
+            return FutureResult::Complete.new([])
           else
             return []
           end

activerecord/test/cases/relation/load_async_test.rb

@@ -41,6 +41,18 @@ def test_scheduled?
       assert_not_predicate deferred_posts, :scheduled?
     end
 
+    def test_null_scheduled?
+      deferred_null_posts = Post.none.load_async
+      if in_memory_db?
+        assert_not_predicate deferred_null_posts, :scheduled?
+      else
+        assert_predicate deferred_null_posts, :scheduled?
+      end
+      assert_predicate deferred_null_posts, :loaded?
+      deferred_null_posts.to_a
+      assert_not_predicate deferred_null_posts, :scheduled?
+    end
+
     def test_reset
       deferred_posts = Post.where(author_id: 1).load_async
       if in_memory_db?