better form validation for new challenge

rowers/models.py

@@ -578,12 +578,16 @@ def course_length(course):
 
         totaldist += 1000.*dist[0]
 
-    vector = get_dir_vector(polygons[0],polygons[1])
+    try:
-    deltastart = get_delta(vector,polygons[0])
+        vector = get_dir_vector(polygons[0],polygons[1])
+        deltastart = get_delta(vector,polygons[0])
 
-    polygons = polygons.reverse()
+        polygons = polygons.reverse()
-    vector = get_dir_vector(polygons[0],polygons[1])
+        vector = get_dir_vector(polygons[0],polygons[1])
-    deltafinish = get_delta(vector,polygons[0])
+        deltafinish = get_delta(vector,polygons[0])
+    except IndexError:
+        deltastart = 0
+        deltafinish = 0
 
     return int(totaldist-deltastart-deltafinish)
 
@@ -2644,14 +2648,31 @@ class VirtualRaceForm(ModelForm):
             startdatetime
         )
 
-        end_time = cd['end_time']
+        try:
+            end_time = cd['end_time']
+        except KeyError:
+            raise forms.ValidationError(
+            'Must have end time',
+            code='missing endtime'
+            )
+
+
         if end_time is None:
             raise forms.ValidationError(
                 'Must have end time',
                 code='missing endtime'
                 )
 
-        end_date = cd['enddate']
+        try:
+            end_date = cd['enddate']
+        except KeyError:
+            raise forms.ValidationError(
+                'Missing or invalid end date',
+                code='missing end date'
+            )
+
+
+
         enddatetime = datetime.datetime.combine(end_date,end_time)
         enddatetime = pytz.timezone(timezone_str).localize(
             enddatetime