Error Messages at top of screen

I really want to use this plugin. It’s intuitive and gives great customization power over single post templates. I’m having a problem, however.

When I activate the template I want to use in the “Options” menu, I get the following errors showing at the top of my browser:

Warning: Illegal string offset ‘media_type’ in /homepages/13/d744808308/htdocs/clickandbuilds/MattyMiyamoto/wp-content/plugins/post-custom-templates-lite/include/classes/otw_pctl_dispatcher.class.php on line 152

Warning: Cannot assign an empty string to a string offset in /homepages/13/d744808308/htdocs/clickandbuilds/MattyMiyamoto/wp-content/plugins/post-custom-templates-lite/include/classes/otw_pctl_dispatcher.class.php on line 152

Since my site is live, I’ve had to disable the plugin and reverted to the theme’s original template file.

Is this a theme issue or is it an incompatibility with WordPress 4.9.8? Let me know if you have any ideas on how to fix this issue when you get a chance.

I’m currently using the Mega Blog theme.

Thanks in advance,

Matty