Fix segfault when leaving loading server list page

TODO.md

@@ -1,8 +1,10 @@
 # TODO
 
+- keep scrollbars auto behavior?
+- improve auto completion delegate
+
 - refresh server list button
 - server list sorting method / explain what the % number is (stability)
-- spam alt+shift+a/going to room when starting app on server browser → segfault
 - login with account already added → infinite spinner in room list
 
 - global presence control

src/gui/Pages/AddAccount/ServerBrowser.qml

@@ -173,6 +173,9 @@ HBox {
 
     onAccepted: window.saveState(this)
 
+    Component.onDestruction:
+        if (fetchServersFuture) fetchServersFuture.cancel()
+
     Timer {
         id: connectTimeout
         interval: 30 * 1000