Fix crash when trying to cancel canceled pester task

- If we try to cancel a pester task that was already canceled and set to
  none an AttributeError might be raised trying to call `cancel()` on
  None. This fix makes sure that pester_task isn't None before canceling.

1 files changed, 1 insertions, 1 deletions

diff --git a/warmachine/addons/standup.py b/warmachine/addons/standup.py
index 15281f5..2a468f4 100644
--- a/warmachine/addons/standup.py
+++ b/warmachine/addons/standup.py
@@ -73,7 +73,7 @@ class StandUpPlugin(WarMachinePlugin):
 
             for_channels = data['for_channels']
 
-            if 'pester_task' in data:
+            if 'pester_task' in data and data['pester_task']:
                 self.log.debug('Stopping pester for {}'.format(user_nick))
                 data['pester_task'].cancel()
                 data['pester_task'] = None