How would you DEBUG that message & interpret it?

I’m getting strange Error messages with Paths. Before it was all working. I’m not sure where to start DEBUG that? Of course I can delete all the image steps in my server actions again and again. But how would you start with that error here and what it tells you?

{"code":0,"file":"C:\\xampp\\htdocs\\project\\dmxConnectLib\\lib\\core\\Path.php","line":41,"message":"Invalid Path! ","trace":"#0 C:\\xampp\\htdocs\\project\\dmxConnectLib\\modules\\image.php(32): lib\\core\\Path::toSystemPath(NULL)\n#1 C:\\xampp\\htdocs\\project\\dmxConnectLib\\lib\\App.php(159): modules\\image->load(Object(stdClass), 'image1')\n#2 C:\\xampp\\htdocs\\project\\dmxConnectLib\\lib\\App.php(128): lib\\App->execSteps(Object(stdClass))\n#3 C:\\xampp\\htdocs\\project\\dmxConnectLib\\lib\\App.php(98): lib\\App->execSteps(Array)\n#4 C:\\xampp\\htdocs\\project\\dmxConnectLib\\lib\\App.php(71): lib\\App->exec(Object(stdClass))\n#5 C:\\xampp\\htdocs\\project\\dmxConnect\\api\\Server Actions\\Clients\\C_quickadvert\\C_quickadvert.php(8): lib\\App->define(Object(stdClass))\n#6 {main}"}<br />
<b>Fatal error</b>:  Uncaught ErrorException: imagedestroy() expects parameter 1 to be resource, null given in C:\xampp\htdocs\project\dmxConnectLib\lib\image\Processor.php:25
Stack trace:
#0 [internal function]: exception_error_handler(2, 'imagedestroy() ...', 'C:\\xampp\\htdocs...', 25, Array)
#1 C:\xampp\htdocs\project\dmxConnectLib\lib\image\Processor.php(25): imagedestroy(NULL)
#2 [internal function]: lib\image\Processor-&gt;__destruct()
#3 {main}
  thrown in <b>C:\xampp\htdocs\project\dmxConnectLib\lib\image\Processor.php</b> on line <b>25</b><br />