Glow MQTT platform not found with Core 2023.9.2

[En-Bee]

Loss of Glow MQTT platform immediately on upgrade to Core 2023.9.2

Log shows:
2023-09-24 09:19:46.428 ERROR (MainThread) [homeassistant.loader] Unexpected exception importing platform custom_components.hildebrand_glow_ihd.sensor
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/loader.py", line 838, in get_platform
cache[full_name] = self._import_platform(platform_name)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/src/homeassistant/homeassistant/loader.py", line 855, in _import_platform
return importlib.import_module(f"{self.pkg_path}.{platform_name}")
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/importlib/init.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "", line 1204, in _gcd_import
File "", line 1176, in _find_and_load
File "", line 1147, in _find_and_load_unlocked
File "", line 690, in _load_unlocked
File "", line 940, in exec_module
File "", line 241, in _call_with_frames_removed
File "/config/custom_components/hildebrand_glow_ihd/sensor.py", line 177, in
"unit_of_measurement": VOLUME_CUBIC_METRES, # Might change to VOLUME_CUBIC_METERS soon
^^^^^^^^^^^^^^^^^^^
NameError: name 'VOLUME_CUBIC_METRES' is not defined
2023-09-24 09:19:46.455 ERROR (MainThread) [homeassistant.setup] Unable to prepare setup for platform hildebrand_glow_ihd.sensor: Platform not found (Exception importing custom_components.hildebrand_glow_ihd.sensor).

Please bare in mind my Newb status, so please be gentle.