Issue with using layoutcomponents in blocks and adding custom block fields to layout

Problem/Motivation

When trying to use layoutcomponents in a custom block type and trying to add the custom block types field , afterwards we can't configure it because of the following error:

Error: Call to a member function get() on bool in Drupal\layoutcomponents\Form\LcUpdateBlockForm->blockContentToInline() (line 160 of /var/www/html/drupal/source/web/modules/contrib/layoutcomponents/src/Form/LcUpdateBlockForm.php)

The problem is that in src/Form/LcUpdateBlockForm.php->buildForm() there is the following condition

if (strpos($conf['id'], 'block_content:') > -1) {
}

Which works great for normal block content because they have the following format block_content:3d55f91a-872a-4819-b5bc-b29184cb98e5 but it also find the following format field_block:block_content:sidebar:id which is the custom block types field value and for this the blockContentToInline function fails.

Steps to reproduce

1.) create a custom block type with some fields
2.) in the layout try adding one of the blocks fields
3.) try to use the wrench icon to configure the block (error is thrown)

Proposed resolution

Change the condition to only search for id which starts with block_content because all the blocks will have the following block_content:UUID

Remaining tasks

User interface changes

API changes

Data model changes