go/graphd: cleanup error check
go/graphd: cleanup error check

Follow Go's idiom of error + immediate error check.

Signed-off-by: pierogmorski <79aded9062554a6c0b4693dd0a70998043054ef9@gmail.com>

googlearchive/graphd,googlearchive/graphd,googlearchive/graphd,googlearchive/graphd,googlearchive/graphd