Block with error disappears

Steps

• Add a block with an exception and try to edit the page
• At https://integrated-latest.e-activesites.nl/search?integrated_website_edit=1 this is already done for the comment block (at 21/6 - an Integrated update will fix the block)

Result 1

I think this result was before the migration to json block editing:

• The message "Block "Comment" contains an error" is shown shortly, but disappears

Result 2

This is the result now:

• The message "Block "Comment" contains an error" is not shown