TypeError: 'WidgetBase::errorElement(): Argument #1 ($element) must be of type array, null given, called in WidgetBase.php'

Not able to reproduce this issue any longer. Thus, can be closed.

I still have this issue even with the dev version of workflow module. If it can help I use a node form including a IEF field referencing an other type node.
This error appears when I click from the original form to had a referencing IEF field and when the form of referencing IEF field appears in my original form I press IEF field cancel button to close it but errors appears and the IEF field form doesn't close.

There is other warning link to this error if it can help :

Undefined array key "original_deltas" in Drupal\Core\Field\WidgetBase->flagErrors() (...web/core/lib/Drupal/Core/Field/WidgetBase.php ligne 576)
Trying to access array offset on value of type null in Drupal\Core\Field\WidgetBase->flagErrors() (...web/core/lib/Drupal/Core/Field/WidgetBase.php ligne 576)
Undefined array key "" in Drupal\Core\Field\WidgetBase->flagErrors() (...web/core/lib/Drupal/Core/Field/WidgetBase.php ligne 577)

There is no issue with version 1.7 of workflow module.
Thanks for your help to resolve this issue.
Regards

It seems that IEF with workflow is not the problem since I used dev version of v.1.8.
First when I upgraded from v.1.7 to dev version of v.1.8, Some fields like language, to state, timestamp and log message was activated in the manage form display menu of my workflow. So I desactivated them as I don't want to display them in my node form.
In my case I used actions button in my node form to change state to an other state status field of my node base on a workflow.
Node creation works perfectly when I use an administrator right. But when I try with a basic right, node creation crashes with the error message :
TypeError : Drupal\Core\Field\WidgetBase::errorElement(): Argument #1 ($element) must be of type array, null given, called in web/core/lib/Drupal/Core/Field/WidgetBase.php on line 580
Why did it work with an administrator right and crash with a basic right ?
With v.1.7 It works fine. Could you help me resolve this issue as I can't upgrade my all core drupal since this issue...
Regards,

With the latest dev version (9197af8754), this error still exist. Thanks for your help.

Please download latest dev. There must be no errors in Workflow now. A lot has been done in the last 2 weeks.

This should be fixed. Please reopen if not.

Just to inform that with the last dev version, there is still this error :TypeError : Drupal\Core\Field\WidgetBase::errorElement(): Argument #1 ($element) must be of type array, null given, called in web/core/lib/Drupal/Core/Field/WidgetBase.php on line 580 in Drupal\Core\Field\WidgetBase->errorElement() (line 646 of web/core/lib/Drupal/Core/Field/WidgetBase.php