Function process_completed_restricted_exit 

pub fn process_completed_restricted_exit(
    locked: &mut Locked<Unlocked>,
    current_task: &mut CurrentTask,
    error_context: &Option<ErrorContext>,
) -> Result<Option<ExitStatus>, Errno>

Finishes current_task updates after a restricted mode exit such as a syscall, exception, or kick.

Returns an ExitStatus if the task is meant to exit.