When a user selects an unknown or invalid locale by using the search syntax:
!qw siemens :de-TW
Before this patch a UnknownLocaleError exception will be rasied:
```
Traceback (most recent call last):
File "SearXNG/searx/search/processors/online.py", line 154, in search
search_results = self._search_basic(query, params)
File "SearXNG/searx/search/processors/online.py", line 128, in _search_basic
self.engine.request(query, params)
File "SearXNG/searx/engines/qwant.py", line 98, in request
q_locale = get_engine_locale(params['language'], supported_languages, default='en_US')
File "SearXNG/searx/locales.py", line 216, in get_engine_locale
locale = babel.Locale.parse(searxng_locale, sep='-')
File "SearXNG/local/py3/lib/python3.8/site-packages/babel/core.py", line 330, in parse
raise UnknownLocaleError(input_id)
```
This patch implements a simple exception handling, since e.g. `de-TW` does not
exists `de` will be used to get engines locale. On invalid terms like `xy-XY`
the default will be returned.
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
ef81d14ccf