API endpoints should return a response, not nil

app/controllers/admin/users_controller.rb

@@ -301,7 +301,7 @@ class Admin::UsersController < Admin::AdminController
     @user.deactivate(current_user)
     StaffActionLogger.new(current_user).log_user_deactivate(@user, I18n.t('user.deactivated_by_staff'), params.slice(:context))
     refresh_browser @user
-    render body: nil
+    render json: success_json
   end
 
   def silence

spec/requests/admin/users_controller_spec.rb

@@ -593,6 +593,19 @@ RSpec.describe Admin::UsersController do
     end
   end
 
+  describe '#deactivate' do
+    fab!(:reg_user) { Fabricate(:active_user) }
+
+    it "returns success" do
+      put "/admin/users/#{reg_user.id}/deactivate.json"
+      expect(response.status).to eq(200)
+      json = ::JSON.parse(response.body)
+      expect(json['success']).to eq("OK")
+      reg_user.reload
+      expect(reg_user.active).to eq(false)
+    end
+  end
+
   describe '#log_out' do
     fab!(:reg_user) { Fabricate(:user) }