Whoops\Exception\ErrorException Array and string offset access syntax with curly braces is deprecated

Cannot use OSS Endpoint Manager due to error as below. This error appears right after you upload the custom module "OSS Endpoint Manager."

 

Whoops\Exception\ErrorException thrown with message "Array and string offset access syntax with curly braces is deprecated"

Stacktrace:
#8 Whoops\Exception\ErrorException in /var/www/html/admin/modules/endpointman/lib/json.class.php:234
#7 Whoops\Run:handleError in /var/www/html/admin/modules/endpointman/Endpointman.class.php:71
#6 require_once in /var/www/html/admin/modules/endpointman/Endpointman.class.php:71
#5 FreePBX\modules\Endpointman:__construct in /var/www/html/admin/libraries/BMO/Self_Helper.class.php:124
#4 FreePBX\Self_Helper:autoLoad in /var/www/html/admin/libraries/BMO/Self_Helper.class.php:63
#3 FreePBX\Self_Helper:injectClass in /var/www/html/admin/libraries/modulefunctions.class.php:2565
#2 module_functions:_runscripts in /var/www/html/admin/libraries/modulefunctions.class.php:2039
#1 module_functions:install in /var/www/html/admin/page.modules.php:299
#0 include in /var/www/html/admin/config.php:477