I have enabled simplenews module in drupal 8 and I am trying to reduce the width of input field from 60 to 30. I am trying to implement form alter hook and have devel module installed. I used dsm($form_id); to identify form and then in order to identify the form attribute to change, I tried to use dsm($form), dpm($form) and print_r($form) and all these are giving white screen of death.
function custom_newsletter_form_alter(&$form, $form_state, $form_id) {
if ($form_id == 'simplenews_subscriptions_block_2138c21c-6453-4b7d-92d6-9407e427a78a') {
dsm($form);
dpm($form);
print_r($form);
}
}
I have tried different drupal 8 installations both localhosted and web hosted, tried with different themes but I am not able to print form. Is there any other way to identify/target correct form attribute to change like DOM inspecter of firebug?