What steps will reproduce the problem?

http://play.golang.org/p/pCybqtn361


What is the expected output? What do you see instead?

The output starts with:

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
    panic: interface conversion: interface is runtime.errorCString, not tabwriter.osError

This second panic message is a bit confusing. It looks a little like there is a bug in
tabwriter. More useful would be something like:

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
    panic: tabwriter: panic during Write


Please use labels and text to provide additional information.

This is a small, easy change. I'm happy to do it.