jwt: claims.go - return stringify(...) instead of adding branch

jwt/claims.go

diff --git a/jwt/claims.go b/jwt/claims.go
index e7c6a00..d3e125d 100644
--- a/jwt/claims.go
+++ b/jwt/claims.go
@@ -117,11 +117,10 @@
 	case string, []string:
 		return t, true
 	case []interface{}:
-		if s, ok := stringify(t); ok {
-			return s, true
-		}
+		return stringify(t)
+	default:
+		return nil, false
 	}
-	return nil, false
 }
 
 func stringify(a []interface{}) ([]string, bool) {