UnsupportedInstanceError

class UnsupportedInstanceError

Raised for an instance whose value this module cannot yet evaluate soundly.

This is reserved for shapes where producing any verdict would risk being wrong – as opposed to Verdict.UNDECIDABLE, which is returned when a constraint is merely outside the evaluable fragment. The current case is an instance that both constructs a value (new Def(...)) and overrides it with declarative bindings in its body (new Def(5) { :>> val = -1; }): the constructed-object scope reflects the constructor arguments and the instance’s own scope reflects the overrides, but no single scope reflects the merged effective value, so the module refuses to guess.