handle early return for None case in _update_template_units for clarity

Author: tasansal

src/mdio/converters/segy.py

@@ -316,12 +316,13 @@ def _get_spatial_coordinate_unit(segy_file_info: SegyFileInfo) -> LengthUnitMode
 
 def _update_template_units(template: AbstractDatasetTemplate, unit: LengthUnitModel | None) -> AbstractDatasetTemplate:
     """Update the template with dynamic and some pre-defined units."""
-    if unit is None:
-        return template
-
     # Add units for pre-defined: angle and azimuth etc.
     new_units = {key: AngleUnitModel(angle=AngleUnitEnum.DEGREES) for key in ANGLE_UNIT_KEYS}
 
+    # If a spatial unit is not provided, we return as is
+    if unit is None:
+        return template
+
     # Dynamically add units based on the spatial coordinate unit
     for key in SPATIAL_UNIT_KEYS:
         current_value = template.get_unit_by_key(key)