account: fix empty vector access

NewAccountModelPimpl::slotProfileUpdated() does an access on first
element on a vector without checking if it's not empty.
This results in immediate crash.
Fixed by checking the empty condition and doing nothing in such case.

Change-Id: I49276e7ddc7034ebac24d1c109313751f06b4746
Tuleap: #1779
Reviewed-by: Anthony Léonard <anthony.leonard@savoirfairelinux.com>

src/newaccountmodel.cpp

@@ -206,7 +206,9 @@ NewAccountModelPimpl::slotAccountRemoved(Account* account)
 void
 NewAccountModelPimpl::slotProfileUpdated(const Profile* profile)
 {
-    emit linked.profileUpdated(profile->accounts().first()->id().toStdString());
+    auto& accounts = profile->accounts();
+    if (!accounts.empty())
+        emit linked.profileUpdated(accounts.first()->id().toStdString());
 }
 
 } // namespace lrc