diff --git a/client/src/json/editor.ts b/client/src/json/editor.ts
index 04b4609..dfa2cb0 100644
--- a/client/src/json/editor.ts
+++ b/client/src/json/editor.ts
@@ -92,7 +92,7 @@ function updateModel() {
         let json = JSON5.parse(editor.getValue());
 
         // Force PARENT edge coordinates, so that Sprotty can draw the graph correctly.
-        let props = json?.properties || {};
+        let props = json.properties || {};
         props["org.eclipse.elk.json.edgeCoords"] = "PARENT";
         json.properties = props;