Silence context for blitting type check exception.

QuLogic · QuLogic · commit fd41efc6cfce · 2020-07-29T22:39:30.000-04:00
The `iter` call is specifically to check the type, so including it as
traceback context is confusing. The `RuntimeError` we raise is the
intended error, and the internal exception is just flow control.
diff --git a/lib/matplotlib/animation.py b/lib/matplotlib/animation.py
@@ -1723,13 +1723,13 @@ def _draw_frame(self, framedata):
 
         if self._blit:
 
-            err = RuntimeError('The animation function must return a '
-                                   'sequence of Artist objects.')
+            err = RuntimeError('The animation function must return a sequence '
+                               'of Artist objects.')
             try:
                 # check if a sequence
                 iter(self._drawn_artists)
             except TypeError:
-                raise err
+                raise err from None
 
             # check each item if is artist
             for i in self._drawn_artists:
