How to debug python app?

[Kamisori]

Hi.
Host: Ubuntu 22.04 x86_64
Device: Pixel 3a, Ubuntu 20.04
Clickable: 8.0.1

I'm trying to install an openconnect client on my phone. If I solve the challenge from the shell side, then there is a problem with the interface.
I installed clickable with the “QML only” profile (according to the documentation at https://docs.innerzaurus.com/en/latest/tools/clickable.html).
I created a simple interface with a Python call on click.
Everything works on emulation, but not on the phone.
The function with a simple print statement works, but with the subshell call it does not, even with a try-except attached.
How can I display the error? Or should I call the shell differently? (To be honest, I don’t really need Python. I can perform all the logical steps in bash.)

main.qml

import QtQuick 2.0
import io.thp.pyotherside 1.0

Rectangle {
    width: 640; height: 480
    color: "#E95420"
    Text {
        id: label
        font.family: "Ubuntu Mono"
        font.pixelSize: 32
        text: "[Nothing here yet]"
        anchors {
            top: parent.top
            left: parent.left
        }
        color: "white"
    }
    MouseArea {
        anchors.fill: parent
        onClicked: {
            py.addImportPath(Qt.resolvedUrl("."));
            py.importModule("hello", function(){
                label.text = py.call_sync("hello.run_netstat_output");
            });
        }
    }
    Python { id: py }
}

hello. py

import subprocess

# hello.py

def hello_world():
    return "Hello from Python!"


def return_shell_output(cmd):
    try:
        out = subprocess.check_output(cmd, shell=True)
        return out.decode("utf-8")
    except subprocess.CalledProcessError as e:
        return f"Error executing command: {e}"

def run_netstat_output():
    return return_shell_output("ls -l") # ls is for the test purpose

[Kamisori]

Here I am with answer to the my own question.
RTFM!
clickable log command very useful.