bugfix: it was not possible to create new locations on the top level – this is now fixed

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

stock/src/main/java/de/srsoftware/umbrella/stock/SqliteDb.java

@@ -1,6 +1,7 @@
 /* © SRSoftware 2025 */
 package de.srsoftware.umbrella.stock;
 
+import static de.srsoftware.tools.Optionals.is0;
 import static de.srsoftware.tools.Optionals.nullIfEmpty;
 import static de.srsoftware.tools.jdbc.Condition.equal;
 import static de.srsoftware.tools.jdbc.Condition.isNull;
@@ -302,11 +303,11 @@ public class SqliteDb extends BaseDb implements StockDb {
 
 	@Override
 	public DbLocation save(DbLocation location) {
-		var parentId = location.parent() == 0 ? null : location.parent();
+		var parentId = is0(location.parent()) ? null : location.parent();
 		if (location.id() == 0) {  // new location
 			try {
 				var rs = insertInto(TABLE_LOCATIONS,OWNER,PARENT_LOCATION_ID,NAME,DESCRIPTION)
-						.values(location.owner().dbCode(),location.parent() == 0 ? null : parentId,location.name(),location.description())
+						.values(location.owner().dbCode(),parentId,location.name(),location.description())
 						.execute(db).getGeneratedKeys();
 				long id = 0;
 				if (rs.next()) id = rs.getLong(1);