return from InotifyEmitter.queue_events() if not launched when thread…

… is inactive (#963)

* return from InotifyEmitter.queue_events() if not launched when thread is inactive

* add logging

* Update inotify.py

src/watchdog/observers/inotify.py

@@ -64,6 +64,7 @@
 
 """
 
+import logging
 import os
 import threading
 from .inotify_buffer import InotifyBuffer
@@ -91,6 +92,9 @@
 )
 
 
+logger = logging.getLogger(__name__)
+
+
 class InotifyEmitter(EventEmitter):
     """
     inotify(7)-based event emitter.
@@ -124,6 +128,9 @@ def on_thread_stop(self):
     def queue_events(self, timeout, full_events=False):
         # If "full_events" is true, then the method will report unmatched move events as separate events
         # This behavior is by default only called by a InotifyFullEmitter
+        if self._inotify is None:
+            logger.error("InotifyEmitter.queue_events() called when the thread is inactive")
+            return
         with self._lock:
             event = self._inotify.read_event()
             if event is None: