fix #416

rowers/models.py

@@ -517,6 +517,10 @@ def course_length(course):
     polygons = GeoPolygon.objects.filter(course=course).order_by("order_in_course")
 
     totaldist = 0
+
+    if not polygons:
+        return 0
+    
     for i in range(len(polygons)-1):
         latitude1,longitude1 = polygon_coord_center(polygons[i])
         latitude2,longitude2 = polygon_coord_center(polygons[i+1])
@@ -2009,6 +2013,7 @@ class PlannedSessionForm(ModelForm):
         super(PlannedSessionForm, self).__init__(*args, **kwargs)
         self.fields['course'].queryset = GeoCourse.objects.all().order_by("country","name")
 
+
 def get_course_timezone(course):
     polygons = GeoPolygon.objects.filter(course = course)
     points = GeoPoint.objects.filter(polygon = polygons[0])