storage: Fix linter issue
storage: Fix linter issue

Go style tries to avoid indented `else` blocks.

keegancsmith/prometheus,alileza/prometheus,Gouthamve/prometheus,gottwald/prometheus,Stackdriver/stackdriver-prometheus,keegancsmith/prometheus,SaltedMan/prometheus-annotated,Conorbro/prometheus,brancz/prometheus,Stackdriver/stackdriver-prometheus,dsymonds/prometheus,alileza/prometheus,Conorbro/prometheus,Colstuwjx/prometheus,amorken/prometheus,kangwoo/prometheus,prometheus/prometheus,alileza/prometheus,AlekSi/prometheus,brancz/prometheus,slok/prometheus,alileza/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,kzittritsch/prometheus,SaltedMan/prometheus-annotated,JavierZunzunegui/prometheus,tomwilkie/prometheus,GoogleCloudPlatform/prometheus,yanghongkjxy/prometheus,dsymonds/prometheus,dsymonds/prometheus,JavierZunzunegui/prometheus,kangwoo/prometheus,AlekSi/prometheus,tomwilkie/prometheus,alileza/prometheus,Colstuwjx/prometheus,Conorbro/prometheus,kangwoo/prometheus,gottwald/prometheus,kzittritsch/prometheus,amorken/prometheus,gottwald/prometheus,SaltedMan/prometheus-annotated,slok/prometheus,Colstuwjx/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,Gouthamve/prometheus,keegancsmith/prometheus,JavierZunzunegui/prometheus,slok/prometheus,Colstuwjx/prometheus,keegancsmith/prometheus,yanghongkjxy/prometheus,amorken/prometheus,tomwilkie/prometheus,yanghongkjxy/prometheus,Stackdriver/stackdriver-prometheus,kzittritsch/prometheus,tomwilkie/prometheus,prometheus/prometheus,brancz/prometheus,kzittritsch/prometheus,keegancsmith/prometheus,SaltedMan/prometheus-annotated,JavierZunzunegui/prometheus,Conorbro/prometheus,agaoglu/prometheus,yanghongkjxy/prometheus,amorken/prometheus,GoogleCloudPlatform/prometheus,kangwoo/prometheus,AlekSi/prometheus,brancz/prometheus,agaoglu/prometheus,dsymonds/prometheus,AlekSi/prometheus,Gouthamve/prometheus,agaoglu/prometheus,Stackdriver/stackdriver-prometheus,gottwald/prometheus,slok/prometheus,Gouthamve/prometheus,agaoglu/prometheus