Exception when dealing with malformed SLD

[timlinux]

When connecting to a GeoNode instance that has a malformed SLD (current hypothesis, still being confirmed), it can return a response that raises an exception in the GeoNode plugin:

An error has occurred while executing Python code: 

TypeError: a bytes-like object is required, not 'str' 
Traceback (most recent call last):
  File "/home/timlinux/.local/share/QGIS/QGIS3/profiles/XXX/python/plugins/qgis_geonode/apiclient/geonode_api_v2.py", line 226, in handle_dataset_list
    parsed_properties = self._get_common_model_properties(raw_brief_ds)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/timlinux/.local/share/QGIS/QGIS3/profiles/XXX/python/plugins/qgis_geonode/apiclient/geonode_api_v2.py", line 374, in _get_common_model_properties
    name=raw_style.get("name", ""), sld_url=self._get_sld_url(raw_style)
                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/timlinux/.local/share/QGIS/QGIS3/profiles/XXX/python/plugins/qgis_geonode/apiclient/geonode_api_v2.py", line 343, in _get_sld_url
    sld_url = url_from_geoserver(self.base_url, sld_url)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/timlinux/.local/share/QGIS/QGIS3/profiles/XXX/python/plugins/qgis_geonode/utils.py", line 57, in url_from_geoserver
    url_path = urlparse(raw_url).path.strip("/")
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: a bytes-like object is required, not 'str'


Python version: 3.12.9 (main, Feb  4 2025, 14:38:38) [GCC 14.2.1 20250322] 
QGIS version: 3.44.2-Solothurn Solothurn, exported 

I have prepared a small fix for this which basically just traps the issue and returns none. Maybe a secondary issue needs to be raised for GeoNode itself once we are clear on the cause.