added check for file length

rowers/dataprep.py

@@ -466,6 +466,11 @@ def new_workout_from_file(r,f2,
         message = "This C2 logbook summary does not contain stroke data. Please download the Export Stroke Data file from the workout details on the C2 logbook."
         return (0,message,f2)
 
+    if fileformat == 'nostrokes':
+        os.remove(f2)
+        message = "It looks like this file doesn't contain stroke data."
+        return (0,message,f2)
+    
     # Some people try to upload RowPro summary logs
     if fileformat == 'rowprolog':
         os.remove(f2)