I recently started my course on ROS2 and i followed a course online. I got through the normal working and RVIZ and now i am working in gazebo simulations. I completed my code and launch file but when i run it my screen is rendered black. I am using ros2 jazzy and the gazebo start up is Harmonic.

The urdf file runs without any errors and other launch files run fine too. I only have the problem with Gazebo sim.

I tried the launch file as shown below

from launch import LaunchDescription
from launch_ros.actions import Node
from launch_ros.parameter_descriptions import ParameterValue
from launch.actions import DeclareLaunchArgument, SetEnvironmentVariable, IncludeLaunchDescription, LogInfo
from launch.substitutions import Command, LaunchConfiguration
from launch.launch_description_sources import PythonLaunchDescriptionSource
import os
from pathlib import Path
from ament_index_python.packages import get_package_share_directory

def generate_launch_description():
    arduinobot_description_dir = get_package_share_directory("arduinobot_des")
    model_arg = DeclareLaunchArgument(
        name="model",
        default_value=os.path.join(get_package_share_directory("arduinobot_des"),   "urdf", "arduinobot.urdf.xacro"),
        description="Absolute path to the robot urdf file"
    )

    gazebo_resource_path = SetEnvironmentVariable(
        name="GZ_SIM_RESOURCE_PATH",
        value=[
            str(Path(arduinobot_description_dir).parent.resolve()),
        ]
    )

    ros_distro = os.environ["ROS_DISTRO"]
    is_ignition = "True" if ros_distro == "humble" else "False"
    physics_engine = "" if ros_distro == "humble" else "--physics-engine gz-physics-bullet-featherstone-plugin"
    robot_description = ParameterValue(Command([
        "xacro ", 
        LaunchConfiguration("model"),
        " is_ignition:=", 
        is_ignition
        ]),
        value_type = str)

    robot_state_publisher_node = Node(
        package="robot_state_publisher",
        executable="robot_state_publisher",
        parameters=[{"robot_description": robot_description,
                     "use_sim_time": True}]
    )

    gazebo = IncludeLaunchDescription(
        PythonLaunchDescriptionSource([
            os.path.join(
                get_package_share_directory("ros_gz_sim"),
                "launch"
               ),   "/gz_sim.launch.py"]
        ),
        launch_arguments=[
            ("gz_args", [" -v 4 -r empty.sdf ", physics_engine])
        ]
    )

    gz_spawn_entity = Node(
        package="ros_gz_sim",
        executable="create",
        output="screen",
        arguments=["-topic", "robot_description",
                   "-name", "arduinobot"]
    )

    gz_ros2_bridge = Node(
        package="ros_gz_bridge",
        executable="parameter_bridge",
        arguments=[
            "/clock@rosgraph_msgs/msg/Clock[gz.msgs.Clock"
        ]
    )
    return LaunchDescription([
        model_arg,
        gazebo_resource_path,
        robot_state_publisher_node,
        gazebo,
        gz_ros2_bridge,
        gz_spawn_entity,
        
 ])