Fix reset DB

The reset of all folders failed when there was no data for a given
folder, as it was not returned by db.ListFolders then. But we don't
really care about that, we can "reset" it anyway...

internal/model/model.go

@@ -1732,15 +1732,9 @@ func (m *Model) CheckFolderHealth(id string) error {
 	return err
 }
 
-func (m *Model) ResetFolder(folder string) error {
-	for _, f := range db.ListFolders(m.db) {
-		if f == folder {
-			l.Infof("Cleaning data for folder %q", folder)
-			db.DropFolder(m.db, folder)
-			return nil
-		}
-	}
-	return fmt.Errorf("Unknown folder %q", folder)
+func (m *Model) ResetFolder(folder string) {
+	l.Infof("Cleaning data for folder %q", folder)
+	db.DropFolder(m.db, folder)
 }
 
 func (m *Model) String() string {