UI Component forms not related with any model throw fatal error

[mgarciaebo]

It seems that it's impossible to create stand-alone forms using UI Components. I mean, simple forms, not attached to a collection (like the standard import-export forms), because Magento expects for a collection in order to apply filters, and a bunch of other things.

Those kind of forms can still be inserted using blocks and layout injection, as usual, but you encourage us to use UI Components. Actually, classes as Backend\Block\Widget\Form and Backend\Block\Widget\Form\Generic, has been deprecated in favor of UI Component implementation, so it makes no sense that this doesn't work.

Preconditions

1. Magento 2.2.2; 2.3-develop
2. Standard LAMP environment - PHP 7.1 - MySQL 5.6

Steps to reproduce

1. Starting from a vanilla Magento, download, install and enable your own sample Form UI Component, following the instructions given at: https://github.com/magento/magento2-samples/tree/master/sample-module-form-uicomponent
2. Go to the URL provided by the extension, which is [magento2-admin-url]/sampleform

Expected result

1. The following sample form should be displayed:
   

Actual result

1. A fatal error is thrown as shown here:
   

[magento-engcom-team]

@mgarciaavz, thank you for your report.
We've acknowledged the issue and added to our backlog.

[mgarciaebo]

I'm working on this #distributed-cd

[magento-engcom-team]

@mgarciaavz thank you for joining. Please accept team invitation here and self-assign the issue.

[mgarciaebo]

Hi @sidolov,

this issue is fixed here: #13574

Regards!