[fix] hardening against arguments of type None, where str or dict is expected

On a long-running server, the tracebacks below can be found (albeit rarely),
which indicate problems with NoneType where a string or another data type is
expected.

result.img_src::

    File "/usr/local/searxng/searxng-src/searx/templates/simple/result_templates/images.html", line 13, in top-level template code
      <img src="" data-src="{{ image_proxify(result.img_src) }}" alt="{{ result.title|striptags }}">{{- "" -}}
      ^
    File "/usr/local/searxng/searxng-src/searx/webapp.py", line 284, in image_proxify
      if url.startswith('//'):
         ^^^^^^^^^^^^^^
    AttributeError: 'NoneType' object has no attribute 'startswith'

result.content::

    File "/usr/local/searxng/searxng-src/searx/result_types/_base.py", line 105, in _normalize_text_fields
      result.content = WHITESPACE_REGEX.sub(" ", result.content).strip()
                       ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
    TypeError: expected string or bytes-like object, got 'NoneType'

html_to_text, when html_str is a NoneType::

    File "/usr/local/searxng/searxng-src/searx/engines/wikipedia.py", line 190, in response
      title = utils.html_to_text(api_result.get('titles', {}).get('display') or api_result.get('title'))
    File "/usr/local/searxng/searxng-src/searx/utils.py", line 158, in html_to_text
      html_str = html_str.replace('\n', ' ').replace('\r', ' ')
                 ^^^^^^^^^^^^^^^^
    AttributeError: 'NoneType' object has no attribute 'replace'

presearch engine, when json_resp is a NoneType::

    File "/usr/local/searxng/searxng-src/searx/engines/presearch.py", line 221, in response
      results = parse_search_query(json_resp.get('results'))
    File "/usr/local/searxng/searxng-src/searx/engines/presearch.py", line 161, in parse_search_query
      for item in json_results.get('specialSections', {}).get('topStoriesCompact', {}).get('data', []):
                  ^^^^^^^^^^^^^^^^
    AttributeError: 'NoneType' object has no attribute 'get'

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/searx/result_types/_base.py b/searx/result_types/_base.py
index caf7e2a4f..ce846c3cf 100644
--- a/searx/result_types/_base.py
+++ b/searx/result_types/_base.py
@@ -103,8 +103,10 @@ def _normalize_text_fields(result: MainResult | LegacyResult):
         result.content = str(result)
 
     # normalize title and content
-    result.title = WHITESPACE_REGEX.sub(" ", result.title).strip()
-    result.content = WHITESPACE_REGEX.sub(" ", result.content).strip()
+    if result.title:
+        result.title = WHITESPACE_REGEX.sub(" ", result.title).strip()
+    if result.content:
+        result.content = WHITESPACE_REGEX.sub(" ", result.content).strip()
     if result.content == result.title:
         # avoid duplicate content between the content and title fields
         result.content = ""