Add some info about the failed instance when dumping serialization fails.
Add some info about the failed instance when dumping serialization fails.

malkavi/Flexget,ianstalk/Flexget,Flexget/Flexget,malkavi/Flexget,crawln45/Flexget,Flexget/Flexget,crawln45/Flexget,Flexget/Flexget,ianstalk/Flexget,Flexget/Flexget,malkavi/Flexget,crawln45/Flexget,ianstalk/Flexget,malkavi/Flexget,crawln45/Flexget