Add info when no recent edit history to display

app/src/frontend/pages/changes.tsx

@@ -1,6 +1,7 @@
 import React, { useEffect, useState } from 'react';
 
 import { BuildingEditSummary } from '../building/edit-history/building-edit-summary';
+import InfoBox from '../components/info-box';
 import { EditHistoryEntry } from '../models/edit-history-entry';
 
 const ChangesPage = () => {
@@ -23,7 +24,9 @@ const ChangesPage = () => {
                 <h1>Global edit history</h1>
 
                 <ul className="edit-history-list">
-                    {history && history.map(entry => (
+                    {(history == undefined || history.length == 0) ?
+                        <InfoBox msg="No changes in the last week"></InfoBox> :
+                        history.map(entry => (
                             <li key={`${entry.revision_id}`} className="edit-history-list-element">
                                 <BuildingEditSummary
                                     historyEntry={entry}
@@ -31,7 +34,8 @@ const ChangesPage = () => {
                                     hyperlinkCategories={true}
                                 />
                             </li>
-                    ))}
+                        ))
+                    }
                 </ul>
             </section>
         </article>