Add a flash error where no available shipping methods to the customer

+ update specs as well

app/controllers/split_checkout_controller.rb

@@ -21,6 +21,10 @@ class SplitCheckoutController < ::BaseController
 
   def edit
     redirect_to_step_based_on_order unless params[:step]
+
+    return if available_shipping_methods.any?
+
+    flash[:error] = I18n.t('split_checkout.errors.no_shipping_methods_available')
   end
 
   def update

config/locales/en.yml

@@ -1898,6 +1898,7 @@ en:
       invalid_email: "Please enter a valid email address"
       select_a_shipping_method: Select a shipping method
       select_a_payment_method: Select a payment method
+      no_shipping_methods_available: Checkout is not possible due to absence of shipping options. Please contact the shop owner.
   order_paid: PAID
   order_not_paid: NOT PAID
   order_total: Total order

spec/system/consumer/split_checkout_spec.rb

@@ -142,6 +142,23 @@
       expect_to_be_on_first_step
     end
 
+    context "when no shipping methods are available" do
+      before do
+        shipping_methods.each { |sm| sm.update(tag_list: "hidden") }
+      end
+
+      it "should display an error message" do
+        create(:filter_shipping_methods_tag_rule,
+               enterprise: distributor,
+               is_default: true,
+               preferred_shipping_method_tags: "hidden",
+               preferred_matched_shipping_methods_visibility: 'hidden')
+
+        visit checkout_path
+        expect(page).to have_content "Checkout is not possible due to absence of shipping options. Please contact the shop owner."
+      end
+    end
+
     it "should display error when fields are empty" do
       click_on "Checkout as guest"
       click_button "Next - Payment method"