gcp: check if bucket exists after client creation

Signed-off-by: Eric Briand <eric.briand@gmail.com>

src/cmd/linuxkit/push_gcp.go

@@ -52,15 +52,15 @@ func pushGcp(args []string) {
 		name = filepath.Base(name)
 	}
 
-	if bucket == "" {
-		log.Fatalf("Please specify the bucket to use")
-	}
-
 	client, err := NewGCPClient(keys, project)
 	if err != nil {
 		log.Fatalf("Unable to connect to GCP: %v", err)
 	}
 
+	if bucket == "" {
+		log.Fatalf("Please specify the bucket to use")
+	}
+
 	err = client.UploadFile(path, name+suffix, bucket, public)
 	if err != nil {
 		log.Fatalf("Error copying to Google Storage: %v", err)