Fuzz bug: invalid heap2local output

[tlively]

;; test.wast
(module
 (rec
  (type $struct (sub final (shared (descriptor $desc (struct)))))
  (type $desc (sub (shared (describes $struct (descriptor $meta (struct))))))
  (type $meta (sub final (shared (describes $desc (struct)))))
 )

 (func $test
  (local $meta (ref $meta))
  (local.set $meta
   (struct.new_default $meta)
  )
  (drop
   (if (result (ref i31))
    (ref.is_null
     (ref.cast_desc (ref $desc)
      (struct.new_default $desc
       (struct.new_default $meta)
      )
      (local.get $meta)
     )
    )
    (then
     (ref.i31
      (i32.const 0)
     )
    )
    (else
     (ref.as_non_null
      (ref.null none)
     )
    )
   )
  )
 )
)

wasm-opt -all test.wast --heap2local

[wasm-validator error in function test] unexpected false: unreachable instruction must have unreachable child, on...
[wasm-validator error in function test] (ref none) != unreachable: unreachable if-else must have unreachable false, on...