I got the errors like this:

$ launchctl unload some.thing.plist
Unload failed: 5: Input/output error
Try running `launchctl bootout` as root for richer errors.
$ launchctl load some.thing.plist
Load failed: 5: Input/output error
Try running `launchctl bootstrap` as root for richer errors.

I resolved this error with:

$ plutil -lint some.thing.plist
localai.localai.plist: Encountered unexpected character s on line 11 while looking for close tag

• #NOTE: We have the tool plutil for #launchctl or #plist linting.