Prevent disabled primary accounts

app/src/main/java/eu/faircode/email/AdapterAccount.java

@@ -492,6 +492,7 @@ public class AdapterAccount extends RecyclerView.Adapter<AdapterAccount.ViewHold
                 popupMenu.getMenu().add(Menu.NONE, R.string.title_account_ondemand, order++, R.string.title_account_ondemand)
                         .setCheckable(true).setChecked(account.ondemand);
             }
+            if (account.synchronize)
                 popupMenu.getMenu().add(Menu.NONE, R.string.title_primary, order++, R.string.title_primary)
                         .setCheckable(true).setChecked(account.primary);
             if (parentFragment instanceof FragmentAccounts)
@@ -600,6 +601,7 @@ public class AdapterAccount extends RecyclerView.Adapter<AdapterAccount.ViewHold
                                     db.account().setAccountWarning(id, null);
                                     db.account().setAccountError(id, null);
                                     db.account().setAccountConnected(id, null);
+                                    db.account().setAccountPrimary(id, false);
                                 }
 
                                 db.account().setAccountSynchronize(id, sync);