PHP 8 - TypeError: Illegal offset type in isset or empty in OptionsBase.php

This still causes an error for me when using the updated code from this issue. The new condition still fails and therefore this code is not run:

$value = $class::processValue($element, $value);

The new condition also has an illegal isset() function that returns false so I changed this:

if (is_array($value) && count($value) === 2 && array_key_exists($type, $value) && isset($value['other']))

to this:

if (is_array($value) && count($value) === 2 && array_key_exists($type, $value) && array_key_exists('other', $value))

And now the code is working if the value of $value['other'] is empty or null.

Attached patch makes this change

So, that means $value['other'] is NULL? Is my understanding right?

Could you give more details about how to reproduce the error you came across?

Yes, $value['other'] == NULL in my scenario.

The element looks like this:

product_list_attached:
        '#type': radios_other
        '#title': 'Product list attached'
        '#options':
          1: 'Yes - I will attach'
        '#other__type': textarea
        '#other__option_label': 'No - explain:'
        '#other__placeholder': ''
        '#required': true

In the submission triggering the error, option 1 was selected and so the $value array was:

Array
(
    [radios] => 1
    [other] => 
)

I am still facing this issue on version 6.2.9.

Try the following form YAML:

page_1:
  '#type': wizard_page
  '#title': 'Page 1'
  name:
    '#type': textfield
    '#title': Name
    '#required': true
  email:
    '#type': email
    '#title': Email
  require_interpreter_assistance:
    '#type': radios
    '#title': 'Do you require interpreter assistance for the interview?'
    '#options':
      1: 'Language interpreter'
      2: 'Auslan interpreter'
      3: 'Not required'
    '#options_display': buttons
  language_required_for_interpreter:
    '#type': select_other
    '#title': 'Chose the language required for the interpreter'
    '#options':
      1: Urdu
      2: Punjabi
      3: 'Filipino/ Tagalog'
      4: Greek
      5: Maltese
    '#other__option_label': 'Other language'
    '#other__placeholder': ''
    '#other__description': 'Enter language'
    '#states':
      visible:
        ':input[name="require_interpreter_assistance"]':
          value: '1'
summary:
  '#type': wizard_page
  '#title': Summary
  markup:
    '#type': markup
    '#markup': '<p>You are about to submit</p>'
  data_summary:
    '#type': computed_token
    '#title': Summary
    '#display_on': form
    '#mode': html
    '#template': '[webform_submission:values]'
actions:
  '#type': webform_actions
  '#title': 'Submit button(s)'

If I remove `computed_token` field, the problem is gone.