[tasks] Log exception when something failed to logging.

discord/ext/tasks/__init__.py

@@ -3,11 +3,14 @@ import aiohttp
 import websockets
 import discord
 import inspect
+import logging
 
 from discord.backoff import ExponentialBackoff
 
 MAX_ASYNCIO_SECONDS = 3456000
 
+log = logging.getLogger(__name__)
+
 class Loop:
     """A background task helper that abstracts the loop and reconnection logic for you.
 
@@ -86,6 +89,9 @@ class Loop:
         except asyncio.CancelledError:
             self._is_being_cancelled = True
             raise
+        except Exception as e:
+            log.exception('Internal background task failed.')
+            raise
         finally:
             await self._call_loop_function('after_loop')
             self._is_being_cancelled = False