Error: Data structure returned is not convertible in the requested format: Only integer keys supported for array columns on base level. Unsupported string 'firstVisit' found for row 'array (
  'date' => 1698599276,
  'prettyDate' => 'Sunday, October 29, 2023',
  'daysAgo' => 179,
  'referrerType' => false,
  'referrerUrl' => '',
  'referralSummary' => 'Direct Entry',
)'. Try to call this method with the parameters '&format=original&serialize=1'; you will get the original php data structure serialized.