Undefined property: FieldCollectionItemEntity:: Notice: Undefined property: FieldCollectionItemEntity::$field_wa_thick
  in _get_details() (line 385 of ...../er.module).
  
  Warning: array_key_exists() expects parameter 2 to be array, null
  given in _get_details()


The error is on the following line:

$wt = ((array_key_exists('und',$li[$li_id]-&gt;field_wa_thick))?$li[$li_id]-&gt;field_wa_thick['und'][0]['value'] : NULL );


What may be the reason for the following error above??
By allowing only if the value is set the error disappeared. 

if (isset($li[$li_id]-&gt;field_wa_thick['und']) {
  $wt = $li[$li_id]-&gt;field_wa_thick['und'][0]['value'];
}


Also applying the isset if the value is used elsewhere.