warning when creating new page "implode(): Invalid arguments "

[jmyt8]

Describe the bug:
Block editor (Gutenberg) returns warning when creating new page.
Warning: implode(): Invalid arguments passed in ../wp-admin/edit-form-blocks.php on line 251

To Reproduce:
Go to > Pages > Add new

Additional context:
editing existing pages show no warning.
problem existed on a multisite (wp version 5.0.2) with 4 sites. warning shows up in two exising sites and any new site created.
all plugins deactivated.

[aduth]

Since this is an issue in a core file (wp-admin/edit-form-blocks.php), it should be reported to Trac instead. I've created a Trac ticket, including some possible debugging hints (if it sounds familiar why for your site there may not be a post or user known for the created post).

https://core.trac.wordpress.org/ticket/47013