add exception

fet2020/tasks/views.py

@@ -4,6 +4,7 @@ from collections import deque
 
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.contrib.auth.models import User
+from django.core.exceptions import ObjectDoesNotExist
 from django.shortcuts import render
 from django.views.generic.detail import DetailView
 from django.views.generic.edit import CreateView, UpdateView
@@ -121,7 +122,10 @@ class TaskDetailView(LoginRequiredMixin, DetailView):
 
         docus = Document.objects.filter(task__id=self.object.id).order_by("-date")
         context["documents"] = docus
+        try:
             context["topic"] = Topic.objects.get(task_list=self.object.task_list)
+        except ObjectDoesNotExist:
+            context["topic"] = None
         return context