User: Handle unique constraints errors (#101274)

* Handle unique constraints errors

pkg/services/user/userimpl/store.go

@@ -2,11 +2,15 @@ package userimpl
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
 	"time"
 
+	"github.com/go-sql-driver/mysql"
+	"github.com/mattn/go-sqlite3"
+
 	"github.com/grafana/grafana/pkg/events"
 	"github.com/grafana/grafana/pkg/infra/db"
 	"github.com/grafana/grafana/pkg/infra/log"
@@ -72,7 +76,7 @@ func (ss *sqlStore) Insert(ctx context.Context, cmd *user.User) (int64, error) {
 		return nil
 	})
 	if err != nil {
-		return 0, err
+		return 0, handleSQLError(err)
 	}
 
 	return cmd.ID, nil
@@ -580,3 +584,30 @@ func setOptional[T any](v *T, add func(v T)) {
 		add(*v)
 	}
 }
+
+func handleSQLError(err error) error {
+	if isUniqueConstraintError(err) {
+		return user.ErrUserAlreadyExists
+	}
+	return err
+}
+
+func isUniqueConstraintError(err error) bool {
+	// check mysql error code
+	var me *mysql.MySQLError
+	if errors.As(err, &me) && me.Number == 1062 {
+		return true
+	}
+
+	// for postgres we check the error message
+	if strings.Contains(err.Error(), "duplicate key value") {
+		return true
+	}
+
+	var se sqlite3.Error
+	if errors.As(err, &se) && se.ExtendedCode == sqlite3.ErrConstraintUnique {
+		return true
+	}
+
+	return false
+}