fix: complete exploration data flow

backend/internal/models/identity.go

@@ -2,6 +2,7 @@ package models
 
 import (
 	"database/sql"
+	"errors"
 
 	"github.com/google/uuid"
 	"gorm.io/gorm"
@@ -28,6 +29,9 @@ func (m *SaDatasetSource) BeforeCreate(tx *gorm.DB) error {
 	if m.CreatedBy == 0 {
 		m.CreatedBy = m.OwnerID
 	}
+	if m.OwnerID == 0 {
+		return errors.New("dataset source owner is required")
+	}
 	if err := resolveIdentity(tx, &SaUser{}, m.OwnerID, &m.OwnerIdentity); err != nil {
 		return err
 	}