Hi, @skillet. Sorry that you've run into an issue.
I just deleted my installed version of Engine.log Tool and downloaded a fresh copy from above (just to check sure there wasn't an issue with the upload). The fresh copy is operating as expected for me.
I've not seen that error, and that message is very odd. I really wonder if it's related to the macro.
Have you successfully used previous versions of Engine.log Tool?
What version of macOS and Keyboard Maestro are you using?
I suggest you check the Engine.log the old fashioned way (Help > Open Logs Folder) and see if it includes any clues.
If nothing, I suggest you refer to the General Troubleshooting section of this wiki page: KM Troubleshooting