message: Don't attempt to split settings tabs
  Prevents a null pointer dereference when attempting to split a settings tab, due to it not being a terminal tab.
  * [x] Closes
  ## Validation Steps Performed
  Manually tested.
diff: @@ -1822,11 +1822,19 @@ namespace winrt::TerminalApp::implementation
  // Instead, let's just promote this first split to be a tab instead.
  // Crash avoided, and we don't need to worry about inserting a new-tab
  // command in at the start.
  - if (!focusedTab && _tabs.Size() == 0)
  + if (!focusedTab)
  + {
  + if (_tabs.Size() == 0)
  {
  _CreateNewTabFromPane(newPane);
  }
  else
  + {
  + // The focused tab isn't a terminal tab
  + return;
  + }
  + }
  + else
  {
  _SplitPane(*focusedTab, splitDirection, splitSize, newPane);
  }
  