I'm getting a few errors since my host moved me to a new server which has php 7.1. Is anyone able to help with how to address this issue?

Code:
--> PHP Fatal error: Uncaught Error: Cannot use string offset as an array in /home/thegluep/public_html/includes/modules/responsive_sheffield_blue/category_row.php:39
Line 39 of category_row.php contains
PHP Code:
    $list_box_contents[$row][$col] = array('params' => 'class="categoryListBoxContents"' . ' ' . 'style="width:' . $col_width . '%;"',