[tasks] Add indicator for internal task failure

Fixes #2151

discord/ext/tasks/__init__.py

@@ -41,6 +41,7 @@ class Loop:
         self._before_loop = None
         self._after_loop = None
         self._is_being_cancelled = False
+        self._has_failed = False
         self._stop_next_iteration = False
 
         if self.count is not None and self.count <= 0:
@@ -89,7 +90,8 @@ class Loop:
         except asyncio.CancelledError:
             self._is_being_cancelled = True
             raise
-        except Exception as e:
+        except Exception:
+            self._has_failed = True
             log.exception('Internal background task failed.')
             raise
         finally:
@@ -97,6 +99,7 @@ class Loop:
             self._is_being_cancelled = False
             self._current_loop = 0
             self._stop_next_iteration = False
+            self._has_failed = False
 
     def __get__(self, obj, objtype):
         if obj is None:
@@ -155,7 +158,7 @@ class Loop:
             before stopping via :meth:`clear_exception_types` or
             use :meth:`cancel` instead.
 
-        .. versionadded:: 1.2
+        .. versionadded:: 1.2.0
         """
         if self._task and not self._task.done():
             self._stop_next_iteration = True
@@ -254,6 +257,13 @@ class Loop:
         """:class:`bool`: Whether the task is being cancelled."""
         return self._is_being_cancelled
 
+    def failed(self):
+        """:class:`bool`: Whether the internal task has failed.
+
+        .. versionadded:: 1.2.0
+        """
+        return self._has_failed
+
     def before_loop(self, coro):
         """A decorator that registers a coroutine to be called before the loop starts running.