Content Builder for portfolio

Fatal error: Uncaught Error: [] operator not supported for strings in /home/charnock/public_html/wp-content/themes/betheme/includes/content-single-portfolio.php:47 Stack trace: #0 /home/charnock/public_html/wp-includes/template.php(785): require() #1 /home/charnock/public_html/wp-includes/template.php(718): load_template('/home/charnock/...', false, Array) #2 /home/charnock/public_html/wp-includes/general-template.php(204): locate_template(Array, true, false, Array) #3 /home/charnock/public_html/wp-content/themes/betheme/single-portfolio.php(67): get_template_part('includes/conten...', 'single-portfoli...') #4 /home/charnock/public_html/wp-includes/template-loader.php(106): include('/home/charnock/...') #5 /home/charnock/public_html/wp-blog-header.php(19): require_once('/home/charnock/...') #6 /home/charnock/public_html/index.php(17): require('/home/charnock/...') #7 {main} thrown in /home/charnock/public_html/wp-content/themes/betheme/includes/content-single-portfolio.php on line 47