When CATALINA_PID is provided to 'catalina.sh stop -force', but the script doesn't have permission to remove the file, the script instead clears the CATALINA_PID file's contents. The subsequent code for '-force' doesn't account for this and attempts to call kill an empty PID argument, leading to spurious error messages.
Thanks for the report. This has been fixed in trunk and will be included in 8.0.0-RC2 onwards and has also been fixed in 7.0.x for 7.0.43 onwards. I also took the opportunity to fix a related issue if a forced stop is required and the pid file can only be cleared rather than removed.