#445 add documentation

website/reference.py

@@ -868,6 +868,7 @@ You can register coroutines or functions to be called for the following events:
 - `app.on_shutdown`: called when NiceGUI is shut down or restarted
 - `app.on_connect`: called for each client which connects (optional argument: nicegui.Client)
 - `app.on_disconnect`: called for each client which disconnects (optional argument: nicegui.Client)
+- `app.on_exception`: called when an exception occurs (optional argument: exception)
 
 When NiceGUI is shut down or restarted, all tasks still in execution will be automatically canceled.
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