fix next_event and previous_event if there isn't one

lineups/templates/lineups/lineup.html

@@ -2,17 +2,21 @@
 {% with events_active="active" %}
     {% block precontent %}
         <div class="d-flex justify-content-center justify-content-md-center border-bottom bg-white">
+            {% if previous_event %}
                 <a class="btn btn-outline-secondary btn-sm d-md-flex my-auto align-items-md-center my-3 mx-3" href="{% url 'edit lineup' event_id=previous_event.id %}" role="button">
                     <i class="bi bi-chevron-left"></i>{{ previous_event.start|date:"D" }}&nbsp;{{ previous_event.start|date:"n/j" }}
                 </a>
+            {% endif %}
             <div>
                 <h5 class="text-center m-1">{{ event.away_team.name }} vs. {{ event.home_team.name }}</h5>
                 <p class="text-center text-muted m-1">{{ event.start|date:"l, F j, Y g:i A" }}<br>{{ event.venue.name }}</p>
                 <h6 class="text-muted m-1"></h6>
             </div>
+            {% if next_event %}
                 <a class="btn btn-outline-secondary btn-sm align-items-center my-auto my-3 mx-3" href="{% url 'edit lineup' event_id=next_event.id %}" role="button">
                     {{ next_event.start|date:"D" }}&nbsp;{{ next_event.start|date:"n/j" }}<i class="bi bi-chevron-right"></i>
                 </a>
+            {% endif %}
         </div>
 
         <ul class="nav nav-pills nav-fill bg-white" role="tablist">

lineups/views.py

@@ -35,7 +35,7 @@ def edit(request, event_id):
             else:
                 pass
         return render(request, 'success.html', {'call_back':'edit lineup','id':event_id, 'errors':[error for error in formset.errors if error]}, status=200)
-    previous_event = Event.objects.get(id=event_id-1)
+    previous_event = Event.objects.filter(id=event_id-1).first()
 
     event = Event.objects.get(id=event_id)
     next_event = Event.objects.get(id=event_id+1)
@@ -86,7 +86,8 @@ def edit(request, event_id):
     }
 
     return render(request, 'lineups/lineup.html', {'title': 'Lineup',
-                                                   'event': event,                                               'details':details,
+                                                   'event': event,
+                                                   'details':details,
                                                    'previous_event': previous_event,
                                                    'next_event': next_event,
                                                    'formset': formset,