test_errors.py

import pyotherside
import threading
import time

def run():
    while True:
        pyotherside.send("test-errors")
        time.sleep(3)

thread = threading.Thread(target=run)
thread.start()

test_errors.qml

import QtQuick 2.0
import Sailfish.Silica 1.0
import io.thp.pyotherside 1.0

ApplicationWindow {
    initialPage: Page {
        id: page
        Label {
            text: "Testing..."
        }
        function testErrors() {
            console.log("starting");
            page.nonexistentMethod();
            console.log("finished");
        }
    }
    cover: null
    Python {
        id: py
        Component.onCompleted: {
            addImportPath(".");
            importModule("test_errors", null);
            py.setHandler("test-errors", page.testErrors);
        }
        onError: console.log("PYTHON ERROR: " + traceback);
    }
}