Hi,

Sorry about this issue.

We are checking theme with wordpress 5.0. I will release the latest version as soon as possible.

You can use the Classic Editor plugin .

The Classic Editor plugin restores the previous WordPress editor and the Edit Post screen. It lets you keep using plugins that extend it, add old-style meta boxes, or otherwise depend on the previous editor. To install, visit your plugins page and click the “Install Now” button next to “Classic Editor”. After the plugin finishes installing, click “Activate”. That’s it!

You can  go to Plugins > Editor  then edit penci-framework/gutenberg/gutenberg.php file and go to line 74 and remove the code as below:

\
wp_add_inline_script(\
 'penci-gutenberg',\
 sprintf(\
 'var penci_gutenberg = { localeData: %s };',\
 json_encode( gutenberg_get_jed_locale_data( 'penci-gutenberg' ) )\
 ),\
 'before'\
 );\

After remove code,  then update file.

Please check screenshot http://prntscr.com/ls166j, http://prntscr.com/ls16tk, http://prntscr.com/ls16yk

Best Regards,

PenciDesign