store: Show error message when replacing event queue.

Fixes: #555

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

lib/model/store.dart

@@ -785,6 +785,7 @@ class UpdateMachine {
         switch (e) {
           case ZulipApiException(code: 'BAD_EVENT_QUEUE_ID'):
             assert(debugLog('Lost event queue for $store.  Replacing…'));
+            reportErrorToUserBriefly('Reconnecting to server.');
             await store._globalStore._reloadPerAccount(store.accountId);
             dispose();
             debugLog('… Event queue replaced.');

test/model/store_test.dart

@@ -406,7 +406,9 @@ void main() {
       });
       updateMachine.debugAdvanceLoop();
       async.flushMicrotasks();
+      check(debugLastReportedError).isNull();
       await Future<void>.delayed(Duration.zero);
+      check(takeLastReportedError()).isNotNull().contains('Reconnecting to server.');
       check(store).isLoading.isTrue();
 
       // The global store has a new store.