example_91_unhandled_exception.nim needs to specify Layout type.
Example `example_91_unhandled_exception.nim` is missing specification of Layout type in `newLayoutContainer()`

```nim
# This example shows what happens when an unhandled exception occurs in the main loop.

import nigui

app.init()

var window = newWindow()

var container = newLayoutContainer()
window.add(container)

var button = newButton("Raise Exception")
container.add(button)
button.onClick = proc(event: ClickEvent) =
  raise newException(Exception, "Test Exception")

window.show()
app.run()
```

Possible solutions:

1. Change of `var container = newLayoutContainer()` to `var container = newLayoutContainer(Layout_Vertical)`.

2. Set a default for `newLayoutContainer()`