Check the backtrace and look for a line for a file from your code, as opposed to stuff from node_modules or node internals. If you don’t see that then check for the last call to strapi internals and try figure out where it’s getting its data from - in this case I can see:
So check line 82 of that file - It looks like strapi is calling one of node’s path functions with a parameter in an unexpected format - which is probably got from one of your configuration files.