bug fixes

rowers/utils.py

@@ -388,7 +388,10 @@ def wavg(group, avg_name, weight_name):
     In rare instance, we may not have weights, so just return the mean. Customize this if your business case
     should return otherwise.
     """
-    d = group[avg_name]
+    try:
+        d = group[avg_name]
+    except KeyError:
+        return 0
     try:
         w = group[weight_name]
     except KeyError: