ClassCastException when specifying "single cardinality" for edge property

As I understand it, multi-properties are not supported on edges in Tinkerpop, and this is an understandable limitation. However, my expectation as an API client is that if I redundantly specify Cardinality.single when setting a property on an edge, it would succeed silently. Instead AddPropertyStep.java:151,153 (as of 3.4.8) unconditionally casts the traversal element to Vertex on seeing any Cardinality at all, producing a confusing ClassCastException.

(1) In the case of single, which specifies the correct semantics, the call should succeed. (This is relevant when trying to reuse a method to update a single-valued timestamp on a generic Element.)

(2) It would be a major improvement to debugging to, instead of performing inline casting, use a wrapper method producing an error message such as "property cardinality may only be specified for a Vertex".

There are many cases throughout the code where (2) applies; would you be interested in contributions to retrofit enhanced error messages?