improve messages (#123)

src/idpi/metadata.py

@@ -42,7 +42,7 @@ def override(message: bytes, **kwargs: typing.Any) -> dict[str, typing.Any]:
 
     Note that no special consideration is made for maintaining consistency when
     overriding template definition keys such as productDefinitionTemplateNumber.
-    Note that the origin components in x and y will be unset.
+    Note that the origin components in x and y are left untouched.
 
     Parameters
     ----------

src/idpi/operators/destagger.py

@@ -98,7 +98,7 @@ def _update_grid(field: xr.DataArray, dim: Literal["x", "y"]) -> dict[str, Any]:
 
 def _update_vertical(field) -> dict[str, Any]:
     if field.vcoord_type != "model_level":
-        raise ValueError("Field.vcoord_type must model_level")
+        raise ValueError("typeOfLevel must equal generalVertical")
     return metadata.override(
         field.message,
         typeOfLevel="generalVerticalLayer",