I tried both, and things around it, but whatever I did, it would not start the locate script, nor the blinking of the disk visualization. Next release will revert the "-1" change, as it wont accept "Stop" click on the last device. Also cleaned up where the script was loaded twice in different positions. But it won't change your error code, which I don't seem to get myself.
For curiosity, which browser do you use? It works without problem on Chrome, Vivaldi, Firefox for me.