Trouble setting up field instance
SOLVED: 

According to the documentation, the only required properties are field_name, entity_type and bundle.  So I commented out:

'label' =&gt; t('qid'),
'widget' =&gt; array(
  'type' =&gt; 'textfield',
),


And now the field and instance install and uninstall properly.  I'm fairly sure 'textfield' is an inappropriate widget type.