zoho: fix error when region isn't set

backend/zoho/zoho.go

@@ -161,7 +161,7 @@ type Object struct {
 
 func setupRegion(m configmap.Mapper) {
 	region, ok := m.Get("region")
-	if !ok {
+	if !ok || region == "" {
 		log.Fatalf("No region set\n")
 	}
 	rootURL = fmt.Sprintf("https://workdrive.zoho.%s/api/v1", region)