SMURF parser handles relative mesh path wrong

[AlCap23]

The template folder structure for SMURF looks something like

./
 /smurf
  robot.smurf
 /urdf
  robot.urdf
 /meshes
  /stl
   mesh.stl

With matching relative paths for meshes from the urdf file

<visual name="Visual_Mesh">
 <origin xyz="0 0.0 0.0" rpy="0 0 0"/>
  <geometry>
   <mesh filename="../meshes/stl/mesh.stl" scale="1.0 1.0 1.0"/>
   </geometry>
</visual>

And for the smurf file

files:
- ../urdf/robot.urdf

Changing the structure like the following

./
 /smurf
  robot.smurf
 /model
  /urdf
   robot.urdf
  /meshes
   /stl
    mesh.stl

with the corresponding smurf file

files:
- ../model/urdf/robot.urdf

results in an error for loading the model

Everything gets parsed...
mapIndex: 1
smurfing robot: robot...
terminate called after throwing an instance of 'std::runtime_error'
  what():  cannot read node from file

I think we exit with an error! Signal: 6
Aborted (core dumped)

Due to missing meshes. The urdf file on its own is loading fine.