FIX: Invalid creation of `Theme` in wizard builder.

lib/wizard/builder.rb

@@ -138,15 +138,14 @@ class Wizard
 
             theme = Theme.find_by(color_scheme_id: scheme.id)
             name = I18n.t('color_schemes.dark_theme_name')
-            theme ||= Theme.create(name: name, color_scheme_id: scheme.id)
+            theme ||= Theme.create(name: name, color_scheme_id: scheme.id, user_id: @wizard.user.id)
           else
-
             themes = Theme.where(color_scheme_id: nil).order(:id).to_a
             theme = themes.find(&:default?)
             theme ||= themes.first
 
             name = I18n.t('color_schemes.light_theme_name')
-            theme ||= Theme.create(name: name)
+            theme ||= Theme.create(name: name, user_id: @wizard.user.id)
           end
 
           theme.set_default!

spec/components/wizard/step_updater_spec.rb

@@ -160,6 +160,38 @@ describe Wizard::StepUpdater do
       end
     end
 
+    context "without an existing theme" do
+      before do
+        Theme.delete_all
+      end
+
+      context 'dark theme' do
+        it "creates the theme" do
+          updater = wizard.create_updater('colors', base_scheme_id: 'dark', allow_dark_light_selection: true)
+
+          expect { updater.update }.to change { Theme.count }.by(1)
+
+          theme = Theme.last
+
+          expect(theme.user_id).to eq(wizard.user.id)
+          expect(theme.color_scheme.base_scheme_id).to eq('dark')
+        end
+      end
+
+      context 'light theme' do
+        it "creates the theme" do
+          updater = wizard.create_updater('colors', allow_dark_light_selection: true)
+
+          expect { updater.update }.to change { Theme.count }.by(1)
+
+          theme = Theme.last
+
+          expect(theme.user_id).to eq(wizard.user.id)
+          expect(theme.color_scheme).to eq(nil)
+        end
+      end
+    end
+
     context "without an existing scheme" do
       it "creates the scheme" do
         updater = wizard.create_updater('colors', base_scheme_id: 'dark', allow_dark_light_selection: true)