Add an error message when applying UOM to string value type attribute
When changing the value type to string of an attribute with an associated UOM, the following error is observed:
"...cannot be changed to type 'String' because it has a unit of measure and 'String' does not support UOMs."
When you have an existing string type attribute and add a UOM, the value type is automatically changed to a numerical type without warning. It would be helpful to include a similar message as the one mentioned previously.