add exception handling if whitelist does not exist

.ci/generateIndex.py

 import os, re
 from os import path
 from natsort import natsorted
+from pathlib import Path
 
 def line_prepender(filename, line):
     with open(filename, 'r+') as f:
@@ -236,9 +237,10 @@ print("\n > New index generated and saved in " + indexFile)
 
 # write link whitelist out
 whiteListFile = ".ci/whitelist.txt"
-with open(whiteListFile, 'r') as file :
-    for line in file:
-        whiteList += line
+if Path(whiteListFile).exists():
+    with open(whiteListFile, 'r') as file :
+        for line in file:
+            whiteList += line
 
 with open(whiteListFile, 'w') as file:
     file.write(whiteList)