Inside the method:

public static function list_competencies($filters, $sort, $order, $skip, $limit) {

Line 843, the code uses:

foreach ($params['filters'] as $filter) {
  if (!in_array($filter->column, $validcolumns)) {
    throw new invalid_parameter_exception('Filter column was invalid');
  }
  $safefilters[$filter->column] = $filter->value;
}

But, according to the list_competencies_parameters, the $filter is an array, not an sdclass, so when I call the external API, the $filter->column and $filter-> value returns null, where $filter["column"] and $filter["value"] returns correct value.

The correct way should be using an array