I think it's overkill to have a custom exception class here because we want to exit as early as possible. The stack trace useful because it's not a programming error, it's a installation error. I'd prefer having the error string directly and calling `exit` with a non-zero exit code:

```ruby
begin
  require 'rinku'
rescue LoadError => e
  $stderr.puts "Missing dependency 'rinku' for AutolinkFilter. See README.md for details"
end
```