message: wpf: Add a TerminalControlSize emptiness check
  Watson reports show that an "ArgumentException" is being thrown due to `renderSize`
  not being valid. Added a check for renderSize before attempting to resize.
diff: @@ -138,7 +138,7 @@ namespace Microsoft.Terminal.Wpf
  NativeMethods.TerminalSetTheme(this.terminal, theme, fontFamily, fontSize, (int)dpiScale.PixelsPerInchX);
  - if (!this.RenderSize.IsEmpty)
  + if (!this.RenderSize.IsEmpty && !this.TerminalControlSize.IsEmpty)
  {
  this.Resize(this.TerminalControlSize);
  }
  