Fix crash when no id specified

Author: l0drex

src/App.tsx

@@ -50,7 +50,11 @@ class App extends React.Component<any, State> {
   onFileSelected(fileContent) {
     sessionStorage.setItem("familyData", fileContent);
     loadData(JSON.parse(fileContent));
-    window.location.href +="view";
+    if (window.location.href.endsWith("/")) {
+      window.location.href += "view";
+    } else {
+      window.location.href += "/view";
+    }
   }
 
   componentDidMount() {

src/backend/ModelGraph.ts

@@ -58,7 +58,7 @@ class ModelGraph extends GedcomX.Root {
     }
 
     let startPerson: GedcomX.Person;
-    if (startId !== null) {
+    if (startId !== null && startId.length > 0) {
       startPerson = this.getPersonById(startId);
     } else {
       startPerson = this.persons[0];