Fix deprecation check in wx Timer.

anntzer · anntzer · commit ff67bfb23163 · 2018-09-05T12:14:01.000+02:00
Otherwise, breaks e.g. examples/animation/strip_chart.py and likely most
of the animation framework, which calls Timer() with no arguments.
diff --git a/lib/matplotlib/backends/backend_wx.py b/lib/matplotlib/backends/backend_wx.py
@@ -121,7 +121,7 @@ class TimerWx(TimerBase):
     '''
 
     def __init__(self, *args, **kwargs):
-        if isinstance(args[0], wx.EvtHandler):
+        if args and isinstance(args[0], wx.EvtHandler):
             cbook.warn_deprecated(
                 "3.0", "Passing a wx.EvtHandler as first argument to the "
                 "TimerWx constructor is deprecated since %(version)s.")
