Fix 500 error on new contact us form.

If learner has enrollments without course overview object server raises
error, fixed using course_overview property of course enrollment.

LEARNER-4426

lms/djangoapps/support/views/contact_us.py

@@ -32,7 +32,7 @@ class ContactUsView(View):
             tags.append("site_name_{site}".format(site=current_site_name))
 
         if request.user.is_authenticated():
-            context['user_enrollments'] = CourseEnrollment.enrollments_for_user(request.user)
+            context['user_enrollments'] = CourseEnrollment.enrollments_for_user_with_overviews_preload(request.user)
             enterprise_learner_data = enterprise_api.get_enterprise_learner_data(site=request.site, user=request.user)
             if enterprise_learner_data:
                 tags.append('enterprise_learner')

lms/templates/support/contact_us.html

@@ -48,10 +48,12 @@ from openedx.core.djangolib.js_utils import js_escaped_string, dump_js_escaped_j
             % if user_enrollments:
                 enrollments = []
                 % for enrollment in user_enrollments:
-                    enrollments.push({
-                        'course_id': "${enrollment.course.id | n, js_escaped_string}",
-                        'course_name': "${enrollment.course.display_name | n, js_escaped_string}",
-                    })
+                    % if enrollment.course_overview:
+                        enrollments.push({
+                            'course_id': "${enrollment.course_overview.id | n, js_escaped_string}",
+                            'course_name': "${enrollment.course_overview.display_name | n, js_escaped_string}",
+                        })
+                    % endif
                 %endfor
                 context['user']['enrollments'] = enrollments