Subscription stats: Make sure there can be no division by zero errors

sitescripts/templateFilters.py

Index: sitescripts/templateFilters.py
===================================================================
--- a/sitescripts/templateFilters.py
+++ b/sitescripts/templateFilters.py
@@ -165,21 +165,26 @@ def formatbytes(value):
 
 def getsum(iterable, attribute=None):
   if attribute == None:
     return sum(iterable)
   else:
     return sum(item[attribute] for item in iterable)
 
 def getmax(iterable, attribute=None):
-  if attribute == None:
+  if len(iterable) == 0:
+    return 0
+  elif attribute == None:
     return max(iterable)
   else:
     return max(iterable, key=lambda item: item[attribute])[attribute]
 
+def ensuremin(value, minvalue=1):
+  return max(value, minvalue)
+
 def toJSON(value, **args):
   return re.sub(r'</script>', r'<\/script>', json.dumps(value, **args))
 
 filters = {
   'formattime': formattime,
   'timerelative': formatrelativetime,
   'url': formaturl,
   'keepnewlines': formatnewlines,
@@ -191,10 +196,11 @@ filters = {
   'ljust': ljust,
   'rjust': rjust,
   'ltruncate': ltruncate,
   'weekday': formatweekday,
   'monthname': formatmonthname,
   'bytes': formatbytes,
   'sum': getsum,
   'max': getmax,
+  'ensuremin': ensuremin,
   'json': toJSON,
 }