fix #93 crash index template, check nil ptr

pkg/es/index_template.go

@@ -51,7 +51,11 @@ func IndexTemplateList(conf *cfg.Config) error {
 			return fmt.Errorf("failed to unmarshal meta json data: %w", err)
 		}
 
-		table.Entries[idx] = []any{tpl.Name, desc, tpl.IndexTemplate.Priority}
+		var prio int64
+		if tpl.IndexTemplate.Priority != nil {
+			prio = *tpl.IndexTemplate.Priority
+		}
+		table.Entries[idx] = []any{tpl.Name, desc, prio}
 	}
 
 	table.Sort()