Runtime crashes (sometimes) after call to Code.cache_

[stew]

Here's a somewhat minimized example. This will segfault most of the time.

load : '{base.IO, base.Exception} ()
load _ =
  use base.io printLine
  deserialize' : Bytes ->{base.Exception} Code
  deserialize' bs =
    match Code.deserialize bs with
      Right code -> code
      Left text  ->
        base.Exception.raise
          (Failure
            (typeLink DeserializationError) "failed to deserialize code" !Any)
  match Value.deserialize
    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 with
    Left text -> printLine text
    Right a   ->
      use List foldLeft
      use Text ++
      match Value.load a with
        Left terms  ->
          printLine
            (foldLeft (txt t -> txt ++ Term.toText t) "need terms: " terms)
        Right terms ->
          printLine "loaded succesfully"
          terms' = List.map (cases (t, c) -> (t, deserialize' c)) terms
          printLine "deserialized succesfully"
          stillNeeded = cache_ terms'
          printLine "cached successfully"
          printLine
            (foldLeft
              (txt t -> txt ++ " " ++ Term.toText t)
              (   "still need: "
              ++ (Nat.toText (List.size stillNeeded) ++ " terms"))
              stillNeeded)

[stew]

I made some changes on this branch to get us this far: https://github.com/unisonweb/unison/compare/trunk...stew:bug/TermDeserialize?expand=1

[ceedubs]

I'm pretty sure that this was resolved by #2430. Feel free to reopen if I'm wrong.