Array output in ACF fields

[jackfearing]

I recently installed the plugin, using (WP 5.3.2), (ACF 5.8.7), define( 'WP_DEBUG', false ); and after saving the field I'm seeing the information echoed out above the Field Label. (See image attached). Is there something else I need to be dong to void see this message/output?

Also, I looked at the plugin code (slider.class.php) and committed out the print_r($field); which seems to fix the issue. (Screen shot attached

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