bug: ctl: handle non-existing bot modules

the new function utils.get_bot_module_name returns None if a bot module
does not exist, and
importlib.import_module raises an exception when passed None

intelmq/bin/intelmqctl.py

@@ -941,6 +941,12 @@ def check(self, no_connections=False, check_executables=True):
                     check_logger.error('SyntaxError in bot %r: %r', bot_id, exc)
                     retval = 1
                     continue
+                except AttributeError:
+                    # if module does not exist, utils.get_bot_module_name returns None. import_module then raises
+                    # AttributeError: 'NoneType' object has no attribute 'startswith'
+                    check_logger.error('Incomplete installation: Bot %r not importable.', bot_id,)
+                    retval = 1
+                    continue
                 bot = getattr(bot_module, 'BOT')
                 bot_parameters = copy.deepcopy(global_settings)
                 bot_parameters.update(bot_config.get('parameters', {}))  # the parameters field may not exist

intelmq/lib/utils.py

@@ -852,7 +852,10 @@ def _get_console_entry_points():
     return entries.get("console_scripts", [])  # it's a dict
 
 
-def get_bot_module_name(bot_name: str) -> str:
+def get_bot_module_name(bot_name: str) -> Optional[str]:
+    """
+    Returns None if the bot does not exist
+    """
     entries = entry_points()
     if hasattr(entries, "select"):
         entries = tuple(entries.select(name=bot_name, group="console_scripts"))