[ocrfeeder] Handle exceptions when importing PDF

[Joaquim Rocha <jrocha src gnome org>]

commit 403abaa61d20d7afa4682e1c659fd1c77becd4e9
Author: scx <scx mail gmail com>
Date:   Sun Mar 8 23:09:49 2020 +0100

    Handle exceptions when importing PDF
    
    Handle the situation when an error occurs in convertPdfToImages().
    
    convertPdfToImages() may return None when an error occurs,
    but getImagesFromFolder() cannot handle it.
    This patch fixes it.

 src/ocrfeeder/util/lib.py | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/ocrfeeder/util/lib.py b/src/ocrfeeder/util/lib.py
index f2013e0..7b4f096 100644
--- a/src/ocrfeeder/util/lib.py
+++ b/src/ocrfeeder/util/lib.py
@@ -108,6 +108,8 @@ def runGhostscript(dir_name, base_name, pdf_path):
     process = subprocess.run(command, shell=True)
 
 def getImagesFromFolder(folder):
+    if folder is None:
+        return []
     if not os.path.isdir(folder):
         return []
     content = os.listdir(folder)