[resultdb] Log error
[resultdb] Log error

Log error before ignoring it and returning ErrConflict.
This might uncover an error that is not about "row is not found", but
something like "column is not found".

R=332b6c56634d0f63001046c664a2370006a02420@chromium.org

Change-Id: I34e2d43d34ecfd4eabf4dbb91ecd0fd684bc4b42
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2023776
Auto-Submit: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>
Commit-Queue: Chan Li <332b6c56634d0f63001046c664a2370006a02420@chromium.org>
Reviewed-by: Chan Li <332b6c56634d0f63001046c664a2370006a02420@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go