Plugin Formcreator: Failed to get subtype fields

[gillesdubois]

Describe the bug

For some questions type, display is not updated according to question type.
Not impacting all type of question and only present when modifying an existing question.

Note : creating issue for tracking, will try to fix and provide a PR / MR

To Reproduce
Steps to reproduce the behavior:

1. Create a question
2. Set a type
3. Save
4. Change type to "Selection"
5. Fields are not changed to match type

Expected behavior
Fields change trigger a form change

Additional context

Console error : Plugin Formcreator:

Failed to get subtype fields

Php error :

[2023-12-22 11:24:02] glpiphplog.CRITICAL:   *** Uncaught Exception TypeError: i                                                                                                mplode(): Argument #2 ($array) must be of type ?array, stdClass given in /usr/sh                                                                                                are/itsm-ng/plugins/formcreator/inc/field/radiosfield.class.php at line 84
  Backtrace :
  .../formcreator/inc/field/radiosfield.class.php:84 implode()
  .../formcreator/inc/field/selectfield.class.php:47 GlpiPlugin\Formcreator\Fiel                                                                                                d\RadiosField->getDesignSpecializationField()
  plugins/formcreator/ajax/question_design.php:64    GlpiPlugin\Formcreator\Fiel                                                                                                d\SelectField->getDesignSpecializationField()