How to fix this error SLIM APPLICATION ERROR

[areeba]

#0 /opt/unetlab/html/includes/api_topology.php(108): Slim\Slim::handleErrors(8, 'Undefined offse...', '/opt/unetlab/ht...', 108, Array)
#1 /opt/unetlab/html/api.php(616): apiGetLabTopology(Object(Lab))
#2 [internal function]: {closure}(Array)
#3 /opt/unetlab/html/includes/Slim/Route.php(468): call_user_func_array(Object(Closure), Array)
#4 /opt/unetlab/html/includes/Slim/Slim.php(1357): Slim\Route->dispatch()
#5 /opt/unetlab/html/includes/Slim/Middleware/Flash.php(85): Slim\Slim->call()
#6 /opt/unetlab/html/includes/Slim/Middleware/MethodOverride.php(92): Slim\Middleware\Flash->call()
#7 /opt/unetlab/html/includes/Slim/Middleware/PrettyExceptions.php(67): Slim\Middleware\MethodOverride->call()
#8 /opt/unetlab/html/includes/Slim/Slim.php(1302): Slim\Middleware\PrettyExceptions->call()
#9 /opt/unetlab/html/api.php(1339): Slim\Slim->run()
#10 {main}



Kindly guide step by step ASAP

[ecze]

log too short...
Need logs from
/opt/unetlab/data/Logs/api.txt
/opt/unetlab/data/Logs/php_errors.txt
/opt/unetlab/data/Logs/unl_wrapper.txt

E.