fix(backup): null pointer

Author: fiftin

services/project/backup.go

@@ -305,14 +305,15 @@ func (b *BackupDB) format() (*BackupFormat, error) {
 			Inventory, _ = findNameByID[db.Inventory](*o.InventoryID, b.inventories)
 		}
 
-		surveyVars := make([]db.SurveyVar, 0)
-		err := json.Unmarshal([]byte(*o.SurveyVarsJSON), &surveyVars)
-		if err != nil {
-			return nil, err
+		if o.SurveyVarsJSON != nil {
+			surveyVars := make([]db.SurveyVar, 0)
+			err := json.Unmarshal([]byte(*o.SurveyVarsJSON), &surveyVars)
+			if err != nil {
+				return nil, err
+			}
+			o.SurveyVars = surveyVars
 		}
 
-		o.SurveyVars = surveyVars
-
 		templates[i] = BackupTemplate{
 			Template:      o,
 			View:          View,