dirs fails when there is no dirs

[LoLei]

Using the dirs argument with no present dirs in the current dir produces an arguably bad reading error.

$ ./list dirs
ls: cannot access '*/': No such file or directory

Maybe add a case for when there are no directories to produce a better output message?
Also, shouldn't it output at least the . and .. dirs anyway?

[amishbni]

I agree with the first part of your issue, when there's no directories, it shouldn't output anything. This commit should fix that.

As for the second part, I intentionally removed those directories from output, because I don't think seeing them is very useful.