catchError

Runs fn inside an error boundary. If it throws — synchronously, from an effect, or from a rejected derived/action chain — handler(err) is called and the error does not bubble or reach the console. Returns the value of fn, or undefined if it threw.

It is the building block behind <Errored/>; reach for it when you need a programmatic boundary outside JSX.

Arguments

name	type	description
fn	() => T	function to run inside the boundary
handler	(err) => void	handler called for any thrown error

Returns: the return value of fn, or undefined if it threw.

Examples

Programmatic boundary

Catches a throw from inside the boundary and routes it to the handler, which writes the message into a signal instead of letting it surface on the console.

import { catchError, render, root, signal } from 'pota'

function App() {
	const message = signal('not yet')

	root(() => {
		catchError(
			() => {
				throw new Error('boom')
			},
			err => message.write(`caught: ${String(err)}`),
		)
	})

	return <p>{message.read}</p>
}

render(App)