Provide better error message if settings.yml cannot be loaded

Closes #3184

searx/__init__.py

@@ -19,12 +19,22 @@ import logging
 import searx.settings_loader
 from os import environ
 from os.path import realpath, dirname, join, abspath, isfile
+from sys import exit
 
+from searx.exceptions import SearxSettingsException
 
 searx_dir = abspath(dirname(__file__))
 engine_dir = dirname(realpath(__file__))
 static_path = abspath(join(dirname(__file__), 'static'))
-settings, settings_load_message = searx.settings_loader.load_settings()
+
+settings, settings_outgoing = {}, ''
+try:
+    settings, settings_load_message = searx.settings_loader.load_settings()
+except SearxSettingsException as e:
+    logger = logging.getLogger('searx')
+    logger.error('Failed to load settings file: {}'.format(str(e)))
+    exit(1)
+
 
 if settings['ui']['static_path']:
     static_path = settings['ui']['static_path']

searx/settings_loader.py

@@ -112,8 +112,16 @@ def is_use_default_settings(user_settings):
 def load_settings(load_user_setttings=True):
     default_settings_path = get_default_settings_path()
     user_settings_path = get_user_settings_path()
+
+    # no user settings
     if user_settings_path is None or not load_user_setttings:
-        # no user settings
+        if default_settings_path is None:
+            raise SearxSettingsException(
+                'missing default settings.yml file and there is no user configured file.\n'
+                'Please create a configuration file and put it under the root of searx or in /etc/searx or'
+                'configure the path in SEARX_SETTINGS_PATH.',
+                None,
+            )
         return (load_yaml(default_settings_path),
                 'load the default settings from {}'.format(default_settings_path))