[foxy] Different results when using xacro from launch and command line

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Hello,

I have a .xacro file I want to convert to .urdf in order to launch a robot_state_publisher node with it.

If i use xacro in command line then launch the node with the resulting urdf file, everything works fine:

xacro path/to/xacro/suitee.xacro > out.urdf
ros2 run robot_state_publisher robot_state_publisher out.urdf

I have however created a launch file that consists of the following:

from ament_index_python import get_package_share_directory
from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration, Command
from launch_ros.actions import Node
import os


def generate_launch_description():
    use_sim_time = LaunchConfiguration('use_sim_time', default='false')
    suitee_xacro = os.path.join(get_package_share_directory('s_description'), 'urdf', 'suitee.xacro')

    return LaunchDescription([
        DeclareLaunchArgument(
            'use_sim_time',
            default_value='false',
            description='Use simulation (Gazebo) clock if true'),

        Node(
            package='robot_state_publisher',
            executable='robot_state_publisher',
            name='robot_state_publisher_robot',
            output='screen',
            parameters=[{
                'use_sim_time': use_sim_time,
                'robot_description': Command(['xacro', ' ', suitee_xacro])
            }]),
    ])

When I try to launch this file, I have the following error:

 yaml.scanner.ScannerError: while scanning for the next token
 found character '\t' that cannot start any token
  in "<unicode string>", line 47, column 1:
      <xacro:insert_block name="s ...
   ^

I dont know why this happens here and not when i convert xacro on command line, any insights on this ?

I can provide xacro file if needed.