small fix workout library

rowers/utils.py

@@ -845,6 +845,9 @@ def step_to_time_dist(step, avgspeed=3.2, ftp=200, ftspm=25, ftv=3.7, powerzones
         seconds = distance/avgspeed
         rscore = 60.*float(seconds)/3600.
 
+        if targettype is None:
+            return seconds, distance, rscore
+
         if targettype.lower() in ['speed', 'speedlap','speed_lap']:  # pragma: no cover
             value = step.get('targetValue', 0)
             valuelow = step.get('targetValueLow', 0)