Yes! I have found a way.
I had to find the line in the plugin editor that was causing the error. In your case, line 1430 of the User Access Manager. In my case, line 570 of the Advanced Access Manager.
I added the ((array in the proper location following these instructions and the error disappeared:
https://icode4you.net/fixing-the-warning-array_merge-function-array-merge-error-in-wordpresss-wp-ecommerce-plugin
