make ui at least usable throughout

frontend/lib/modules/current_trip_loading_indicator.dart

@@ -0,0 +1,60 @@
+import 'package:flutter/material.dart';
+import 'package:auto_size_text/auto_size_text.dart';
+
+import 'package:anyway/structs/trip.dart';
+import 'package:anyway/pages/current_trip.dart';
+
+class CurrentTripLoadingIndicator extends StatefulWidget {
+  final Trip trip;
+  const CurrentTripLoadingIndicator({
+    super.key,
+    required this.trip,
+  });
+
+  @override
+  State<CurrentTripLoadingIndicator> createState() => _CurrentTripLoadingIndicatorState();
+}
+
+class _CurrentTripLoadingIndicatorState extends State<CurrentTripLoadingIndicator> {
+  @override
+  Widget build(BuildContext context) => Center(
+    child: FutureBuilder(
+      future: widget.trip.cityName,
+      builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
+        Widget greeter;
+        Widget loadingIndicator = const Padding(
+          padding: EdgeInsets.only(top: 10),
+          child: CircularProgressIndicator()
+        );
+
+        if (snapshot.hasData) {
+          greeter = AutoSizeText(
+            maxLines: 1,
+            'Generating your trip to ${snapshot.data}...',
+            style: greeterStyle,
+          );
+        } else if (snapshot.hasError) {
+          // the exact error is shown in the central part of the trip overview. No need to show it here
+          greeter = AutoSizeText(
+            maxLines: 1,
+            'Error while loading trip.',
+            style: greeterStyle,
+            );
+        } else {
+          greeter = AutoSizeText(
+            maxLines: 1,
+            'Generating your trip...',
+            style: greeterStyle,
+            );
+        }
+        return Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            greeter,
+            loadingIndicator,
+          ],
+        );
+      }
+    )
+  );
+}