add sort support to search, add index fields command, fix error messages (#25)

pkg/es/errors.go

@@ -0,0 +1,40 @@
+/*
+Copyright © 2026 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+package es
+
+import (
+	"fmt"
+
+	"github.com/elastic/go-elasticsearch/v9/typedapi/types"
+)
+
+func esErrorString(err error) string {
+	msg := err.Error()
+
+	switch e := err.(type) {
+	case *types.ElasticsearchError:
+		causes := ""
+
+		for _, cause := range e.ErrorCause.RootCause {
+			causes += fmt.Sprintf("%s\n", *cause.Reason)
+		}
+
+		msg = *e.ErrorCause.Reason + ": " + causes
+	}
+
+	return msg
+}