Add content to show when there are no session dates

When moving a patient to either a community clinic or a school session,
if the upcoming session hasn't been closed but it's also got no dates,
the content should be reflected to show that.

Author: thomasleese

app/views/school_moves/show.html.erb

@@ -42,7 +42,9 @@
   <%= f.govuk_radio_buttons_fieldset :action, legend: { text: "Update the child’s record with this new information?" } do %>
     <%= f.govuk_radio_button :action, :confirm, label: { text: "Update record with new school" }, link_errors: true do %>
       <% if @form.show_move_to_school? %>
-        <% hint = if @school_move.school_session.today_or_future_dates.count == 1
+        <% hint = if @school_move.school_session.today_or_future_dates.count == 0
+               "There is an unscheduled session at #{@school_move.school_session.location.name}."
+             elsif @school_move.school_session.today_or_future_dates.count == 1
                "There is an upcoming session at #{@school_move.school_session.location.name} on #{@school_move.school_session.today_or_future_dates.first.to_fs(:long)}."
              else
                "There are upcoming sessions at #{@school_move.school_session.location.name} on #{@school_move.school_session.today_or_future_dates.map { _1.to_fs(:long) }.to_sentence}."