Fix typo

Change-Id: I8721d7de0df81c790a3e890026edab46ab9f714b
diff --git a/cmd/checker/main.go b/cmd/checker/main.go
index 3789746..77b8d9a 100644
--- a/cmd/checker/main.go
+++ b/cmd/checker/main.go
@@ -62,7 +62,7 @@
 		g.Authenticator = gerrit.NewBasicAuth(string(content))
 	}
 	if *gcpServiceAccount != "" {
-		g.Authenticator, err := NewGCPServiceAccount(*gcpServiceAccount)
+		g.Authenticator, err = NewGCPServiceAccount(*gcpServiceAccount)
 		if err != nil {
 			log.Fatal(err)
 		}