message: fix template error when using network explorer
diff: <h3 class="menu-header">{{
  addressBookEntry
  ? addressBookEntry
  - : ('Account #' + walletAccount.index)
  + : (
  + walletAccount
  + ? ('Account #' + walletAccount.index)
  + : 'External address'
  + )
  }}</h3>
  <hr>
  <div
  