Return None directly if we try to calculate the hash of a file that does not exists

src/yunohost/service.py

@@ -713,6 +713,10 @@ def _get_files_diff(orig_file, new_file, as_string=False, skip_header=True):
 
 def _calculate_hash(path):
     """Calculate the MD5 hash of a file"""
+
+    if not os.path.exists(path):
+        return None
+
     hasher = hashlib.md5()
 
     try: