Update routing and check for page existence in guidance

app/models/form/sales/pages/living_before_purchase.rb

@@ -24,9 +24,9 @@ class Form::Sales::Pages::LivingBeforePurchase < ::Form::Page
   end
 
   def page_routed_to?(log)
-    if form.start_year_2025_or_later?
-      log.resale == 2
-    elsif @joint_purchase
+    return false if form.start_year_2025_or_later? && log.resale != 2
+
+    if @joint_purchase
       log.joint_purchase?
     else
       log.not_joint_purchase? || log.jointpur.nil?

app/views/form/guidance/_financial_calculations_shared_ownership.html.erb

@@ -20,8 +20,8 @@
     <% end %>
      must equal
     the purchase price <%= question_link("value", log, current_user) %>
-    <% stairbought_page = log.form.get_question("stairbought", log).page %>
-    <% if stairbought_page.routed_to?(log, current_user) %>
+    <% stairbought_page = log.form.get_question("stairbought", log)&.page %>
+    <% if stairbought_page&.routed_to?(log, current_user) %>
       multiplied by the percentage bought <%= question_link("stairbought", log, current_user) %>
     <% else %>
       multiplied by the percentage equity stake <%= question_link("equity", log, current_user) %>