Add a missing newline.  Don't panic on an unexpected error type.

Change-Id: I82a4b12c498fbfdf4972737329631c0c02540005
Reviewed-on: https://go-review.googlesource.com/44092
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>