Yes. That was the offending file (works with git not with stable)
The error upon opening the file is:The file /home/steve/Desktop/comets.dat was opened and contained lines longer than the configured Line Length Limit (10.000 characters).
The longest of those lines was 777.258 characters long
Those lines were wrapped and the document is set to read-only mode, as saving will modify its content.
Removing comets.dat from the folder allows 3.5.5 stable to load and run.
I attach comets.dat.