Get better stack trace on spurious error

It appears that the agent is crashing and causing tests to fail
even the post-morten ones.

gui/packages/ubuntupro/integration_test/ubuntu_pro_for_windows_test.dart

@@ -6,6 +6,8 @@ import 'package:integration_test/integration_test.dart';
 import 'package:p4w_ms_store/p4w_ms_store_method_channel.dart';
 import 'package:p4w_ms_store/p4w_ms_store_platform_interface.dart';
 import 'package:path/path.dart' as p;
+// ignore: depend_on_referenced_packages
+import 'package:stack_trace/stack_trace.dart' as stack_trace;
 import 'package:ubuntu_service/ubuntu_service.dart';
 import 'package:ubuntupro/constants.dart';
 import 'package:ubuntupro/core/environment.dart';
@@ -20,6 +22,11 @@ import 'utils/build_agent.dart';
 
 void main() {
   final binding = IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+  FlutterError.demangleStackTrace = (stack) {
+    if (stack is stack_trace.Trace) return stack.vmTrace;
+    if (stack is stack_trace.Chain) return stack.toTrace().vmTrace;
+    return stack;
+  };
 
   // A temporary directory mocking the $env:LocalAppData directory to sandbox our agent.
   Directory? tmp;

gui/packages/ubuntupro/lib/app.dart

@@ -1,6 +1,7 @@
 import 'package:agentapi/agentapi.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
+import 'package:grpc/grpc.dart';
 import 'package:provider/provider.dart';
 import 'package:ubuntu_service/ubuntu_service.dart';
 import 'package:yaru/yaru.dart';
@@ -39,7 +40,13 @@ class Pro4WindowsApp extends StatelessWidget {
                 registerServiceInstance<AgentApiClient>(client);
                 final subscriptionInfo =
                     context.read<ValueNotifier<SubscriptionInfo>>();
-                subscriptionInfo.value = await client.subscriptionInfo();
+                // TODO: Remove this try-catch once the agent stop crashing due lack of MS Store access
+                try {
+                  subscriptionInfo.value = await client.subscriptionInfo();
+                } on GrpcError catch (err) {
+                  debugPrint('$err');
+                  debugPrintStack(maxFrames: 20);
+                }
               },
             ),
             child: const StartupPage(nextRoute: Routes.subscriptionStatus),

gui/packages/ubuntupro/lib/main.dart

@@ -1,6 +1,5 @@
 import 'package:flutter/material.dart';
 import 'package:yaru_widgets/yaru_widgets.dart';
-
 import 'app.dart';
 
 Future<void> main() async {