Thanks for the report. This is probably caused by something unusual/invalid in the file. Some uncommon formatting, invalid escape characters, etc.
To be able to fix it, I would need this complete Php file together with Skipper file with this entity.
It's sufficient to erase all other entities from Skipper project as same as erasing all inner logic from the Php file as long as this error still occurs.
If possible, send such project and php file to my email [email protected]