Sometimes (e.g. when ddg does not have a result item) there is no content and
the engine will fail with an IndexError:
* Error: IndexError
* Percentage: 10
* Parameters: `()`
* File name: `searx/engines/duckduckgo.py:375`
* Function: `response`
* Code: `item["content"] = extract_text(eval_xpath(div_result, './/a[contains(@class, "result__snippet")]')[0])`
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
1ef5c03962