cmd/bench: don't overwrite err when cleaning up tmp dirs for sweet

Currently the sweet function doesn't properly propagate errors because
the error gets overwritten on a successful tmp dir clear. Fix this by
only overwriting the error if nothing else went wrong.

Change-Id: I4bda4a3d1d57fc307647bd5d2af8e4afcaec1de2
Reviewed-by: Michael Pratt <>
Trust: Michael Knyszek <>
Run-TryBot: Michael Knyszek <>
TryBot-Result: Gopher Robot <>
1 file changed