fixed some workoutstate errors

rowers/dataprep.py

@@ -512,6 +512,12 @@ def clean_df_stats(datadf, workstrokesonly=True, ignorehr=True,
     except (KeyError,TypeError) as e:
         pass
 
+    # protect 0 workoutstate values from being nulled
+    try:
+        datadf['workoutstate'] = datadf['workoutstate'] + 1
+    except (KeyError,TypeError) as e:
+        pass
+
 
     try:
         datadf = datadf.clip(lower=0)
@@ -545,6 +551,12 @@ def clean_df_stats(datadf, workstrokesonly=True, ignorehr=True,
     except (TypeError,KeyError) as e:
         pass
 
+    # bring workoutstate back to real values
+    try:
+        datadf['workoutstate'] = datadf['workoutstate'] - 1
+    except (TypeError,KeyError) as e:
+        pass
+
 
     # return from positive domain to negative
     try: