protect against december 31st potential bug

diff --git a/emissions/utils.py b/emissions/utils.py
index e98694abedf0b4601ebea4f73bc97f79a8337d90..6f002f3558507c55945f40191a0b5a7e93e05e92 100644 (file)
--- a/emissions/utils.py
+++ b/emissions/utils.py
@@ -234,7 +234,7 @@ def period_program(date_start, date_end, prefetch_sounds=True,
                         cells.append(cls(nonstop, dt))
 
             cells.sort(key=lambda x: x.datetime)
-            if last_added_end < end:
+            if last_added_end and last_added_end < end:
                 # we used all nonstop slots and we still did not reach the end;
                 # let's go for one more turn.
                 cells.extend(cls.get_serie(last_added_end, end))