尝试更新阵列时出现“间接修改重载属性无效”的错误

I'm attempting to update a nested array in php. However, my updates have no effect. Here's the relevant code:

foreach($form["fields"] as $field){

Populate Checkbox Fields
if($field['type'] == 'checkbox'){
  $inputs = $field['inputs'];
  $count = '0';
  foreach($inputs as $input){
    if(($user_meta[$input['id']] !== '') && (isset($user_meta[$input['id']]))){
       $select = true;
    }
    else{
      $select = false;
    }
    $field['choices'][$count] = array( 'text' => $field['choices'][$count]['text'], 'value' => $field['choices'][$count]['value'] , 'isSelected' => $select );

    $count = $count + '1';
  }
}
}

I've tried a few different workarounds after searching for this error, but none of them seem effective. I'm grateful for any help anyone can offer.

Just use a reference & for $field with your existing code:

foreach($form['fields'] as &$field){

Alternately, use the key and modify the main array:

foreach($form['fields'] as $key => $field){

        // later in the code
        $form['fields'][$key]['choices'][$count] = array( /* ... */ );