[fix] logger per engine: make .logger is always initialized

the openstreetmap engine imports code from the wikidata engine.
before this commit, specific code make sure to copy the logger variable to the wikidata engine.

with this commit searx.engines.load_engine makes sure the .logger is initialized.
The implementation scans sys.modules for module name starting with searx.engines.

searx/engines/__init__.py

@@ -110,10 +110,26 @@ def load_engine(engine_data):
     if is_missing_required_attributes(engine):
         return None
 
-    engine.logger = logger.getChild(engine_name)
+    set_loggers(engine, engine_name)
+
     return engine
 
 
+def set_loggers(engine, engine_name):
+    # set the logger for engine
+    engine.logger = logger.getChild(engine_name)
+    # the engine may have load some other engines
+    # may sure the logger is initialized
+    for module_name, module in sys.modules.items():
+        if (
+            module_name.startswith("searx.engines")
+            and module_name != "searx.engines.__init__"
+            and not hasattr(module, "logger")
+        ):
+            module_engine_name = module_name.split(".")[-1]
+            module.logger = logger.getChild(module_engine_name)
+
+
 def update_engine_attributes(engine, engine_data):
     # set engine attributes from engine_data
     for param_name, param_value in engine_data.items():

searx/engines/openstreetmap.py

@@ -438,8 +438,3 @@ def get_key_label(key_name, lang):
         if labels is None:
             return None
     return get_label(labels, lang)
-
-
-def init(_):
-    import searx.engines.wikidata  # pylint: disable=import-outside-toplevel
-    searx.engines.wikidata.logger = logger