Calling unique() on a standard list of non-immutable classes in Javascript throws NotImmutableErr:

sys::NotImmutableErr: key is not immutable: acme::MyClass
Error
    at fan.sys.Err.$ctor (sys.js:70:16)
    at fan.sys.NotImmutableErr.$ctor (sys.js:186:94)
    at new f (sys.js:10:12)
    at Function.fan.sys.NotImmutableErr.make (sys.js:188:62)
    at fan.sys.Map.set (sys.js:5626:31)
    at fan.sys.List.unique (sys.js:5014:6)

Ticket promoted to #2629 and assigned to andy

Ticket resolved in 1.0.70

Fixed to use an ES6 Map to check dups (which should also be an optimization)

Changeset