explorer crashes attempting Value -> TupleValue cast

[pk19604014]

trafficstars

// Generated by proto_to_carbon.

package EmptyIdentifier impl;

fn apply[T:! Type, U:! Type](f: T, EmptyIdentifier: U)
{
match (true[true]) {}
}

fn EmptyIdentifier() -> apply(true, true);

fn Main() -> i32 {
  return 0;
}

explorer: external/llvm-project/llvm/include/llvm/Support/Casting.h:566: decltype(auto) llvm::cast(const From &) [To = Carbon::TupleValue, From = Carbon::Value]: Assertion `isa<To>(Val) && "cast<Ty>() argument of incompatible type!"' failed.
```