Ensure after is called inside the daemon thread for players.

discord/voice_client.py

@@ -118,9 +118,10 @@ class StreamPlayer(threading.Thread):
         except Exception as e:
             self._current_error = e
             self.stop()
+        finally:
+            self._call_after()
 
-    def stop(self):
-        self._end.set()
+    def _call_after(self):
         if self.after is not None:
             try:
                 arg_count = len(inspect.signature(self.after).parameters)
@@ -136,6 +137,9 @@ class StreamPlayer(threading.Thread):
             except:
                 pass
 
+    def stop(self):
+        self._end.set()
+
     @property
     def error(self):
         return self._current_error