Indexing into a sequence defined as a type does not work

[HrNilsson]

The following class illustrates the bug.

class A

types
    B = seq of real;

operations
    public testTypeIndexing : () ==> ()
    testTypeIndexing() ==
    (
        dcl first : seq of real := [1,2,3],
            second : B := [1,2,3];

        first(1) := 4; -- Works fine
        second(1) := 4; -- Does not work: Error 4020: State value is neither a sequence nor a map in 'A' (...\model_de\A.vdmrt) at line 14:3
    );

thread periodic(1e9, 0, 0, 0)(testTypeIndexing)

end A