Remove csv before renaming only if exist

Author: idanpa

wpm/stats.py

@@ -255,5 +255,6 @@ def save(self, filename):
                 game[0] = 1 + race
                 writer.writerow(game)
 
-        os.remove(filename)
+        if os.path.exists(filename):
+                os.remove(filename)
         os.rename(filename + ".tmp", filename)