RuntimeError: index out of bounds

[tubbadu]

Hello! I'm trying to write my first WebAssembly app, but I'm really struggling to make it work: I removed more and more objects from my Main.qml, always getting lots of errors (while for Desktop it compiles and runs without any issue). I finally removed EVERYTHING from the main, leaving it like this:

import QtQuick
import QtQuick.Window
import QtQuick.Layouts
import QtQuick.Controls

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    TextField {
        text: "hello"
    }
}

and again, in the browser console there's this error:

Uncaught RuntimeError: index out of bounds
    qtStdWebEventCallbackActivate http://localhost:30000/qtloader.js line 461 > eval line 5737 > Function:8
appNandoKaraoke.wasm:15590446:1
    QCursor::shape() const http://localhost:30000/appNandoKaraoke.wasm:15590446
    QWasmCursor::changeCursor(QCursor*, QWindow*) http://localhost:30000/appNandoKaraoke.wasm:12822937
    QWindowPrivate::setCursor(QCursor const*) http://localhost:30000/appNandoKaraoke.wasm:15930234
    QWindow::unsetCursor() http://localhost:30000/appNandoKaraoke.wasm:15930298
    QQuickWindowPrivate::updateCursor(QPointF const&, QQuickItem*) http://localhost:30000/appNandoKaraoke.wasm:6317197
    QQuickDeliveryAgentPrivate::handleMouseEvent(QMouseEvent*) http://localhost:30000/appNandoKaraoke.wasm:6859409
    QQuickDeliveryAgent::event(QEvent*) http://localhost:30000/appNandoKaraoke.wasm:6856495
    QQuickWindow::event(QEvent*) http://localhost:30000/appNandoKaraoke.wasm:6312986
    QCoreApplicationPrivate::notify_helper(QObject*, QEvent*) http://localhost:30000/appNandoKaraoke.wasm:546717
    QCoreApplication::notify(QObject*, QEvent*) http://localhost:30000/appNandoKaraoke.wasm:546880
    QGuiApplication::notify(QObject*, QEvent*) http://localhost:30000/appNandoKaraoke.wasm:15694344
    QCoreApplication::notifyInternal2(QObject*, QEvent*) http://localhost:30000/appNandoKaraoke.wasm:546136
    QCoreApplication::sendSpontaneousEvent(QObject*, QEvent*) http://localhost:30000/appNandoKaraoke.wasm:548648
    QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) http://localhost:30000/appNandoKaraoke.wasm:15700088
    QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) http://localhost:30000/appNandoKaraoke.wasm:15695647
    bool QWindowSystemHelper<QWindowSystemInterface::SynchronousDelivery>::handleEvent<QWindowSystemInterfacePrivate::MouseEvent, QWindow*, unsigned long, QPointF, QPointF, QFlags<Qt::MouseButton>, QFlags<Qt::KeyboardModifier>, Qt::MouseButton, QEvent::Type, Qt::MouseEventSource, bool, QPointingDevice const*>(QWindow*, unsigned long, QPointF, QPointF, QFlags<Qt::MouseButton>, QFlags<Qt::KeyboardModifier>, Qt::MouseButton, QEvent::Type, Qt::MouseEventSource, bool, QPointingDevice const*) http://localhost:30000/appNandoKaraoke.wasm:15953200
    bool QWindowSystemHelper<QWindowSystemInterface::DefaultDelivery>::handleEvent<QWindowSystemInterfacePrivate::MouseEvent, QWindow*, unsigned long, QPointF, QPointF, QFlags<Qt::MouseButton>, QFlags<Qt::KeyboardModifier>, Qt::MouseButton, QEvent::Type, Qt::MouseEventSource, bool, QPointingDevice const*>(QWindow*, unsigned long, QPointF, QPointF, QFlags<Qt::MouseButton>, QFlags<Qt::KeyboardModifier>, Qt::MouseButton, QEvent::Type, Qt::MouseEventSource, bool, QPointingDevice const*) http://localhost:30000/appNandoKaraoke.wasm:15941411
    bool QWindowSystemInterface::handleMouseEvent<QWindowSystemInterface::DefaultDelivery>(QWindow*, unsigned long, QPointF const&, QPointF const&, QFlags<Qt::MouseButton>, Qt::MouseButton, QEvent::Type, QFlags<Qt::KeyboardModifier>, Qt::MouseEventSource) http://localhost:30000/appNandoKaraoke.wasm:15960691
    ClientArea::deliverEvent(PointerEvent const&) http://localhost:30000/appNandoKaraoke.wasm:12878766
    ClientArea::processPointer(PointerEvent const&) http://localhost:30000/appNandoKaraoke.wasm:12878282
    std::__2::__function::__func<ClientArea::ClientArea(QWasmWindow*, QWasmScreen*, emscripten::val)::$_0, std::__2::allocator<ClientArea::ClientArea(QWasmWindow*, QWasmScreen*, emscripten::val)::$_0>, void (emscripten::val)>::operator()(emscripten::val&&) http://localhost:30000/appNandoKaraoke.wasm:12884897
    qstdweb::EventCallback::activate(emscripten::val) http://localhost:30000/appNandoKaraoke.wasm:2016590
    emscripten::internal::Invoker<void, emscripten::val>::invoke(void (*)(emscripten::val), emscripten::_EM_VAL*) http://localhost:30000/appNandoKaraoke.wasm:2004472
    qtStdWebEventCallbackActivate http://localhost:30000/qtloader.js line 461 > eval line 5737 > Function:8

after removing also the TextField the error is no longer present.

Why is this happening? how can I solve this?

with a more complex qml file I get a LOT of this errors, and sometimes the page breaks totally.

[WebAssembly Qt 6.5.2 (single-threaded)]

thanks in advance!

[Elliot Dunk]

First make sure you are compiling with the correct Emscripten version for the Qt version you are using. For Qt 6.5.2 it should be Emscripten 3.1.25. If that doesn't work add this line to your cmake file: target_link_options(PocketSolver PUBLIC -s STACK_SIZE=5MB), this should fix your error.