Segfault when tool method returns a Hash containing a non-primitive value

[tleish]

When a tool method returns a Hash where one of the values is a non-primitive type, calling eval causes a segfault instead of returning an error result.

Reproduction

require "enclave"

class Tools
  Opaque = Struct.new(:x)

  def bad_hash
    { "ok" => "fine", "bad" => Opaque.new("x") }
  end
end

enclave = Enclave.new(tools: Tools.new)
enclave.eval("bad_hash")

Expected: result.error returns "TypeError: unsupported type for sandbox: Tools::Opaque"

Actual: Segfault

[BUG] Segmentation fault at 0x0000000000000020
ruby 3.1.7p261 [arm64-darwin]

-- Ruby level backtrace information ----------------------------------------
test.rb:12:in `<main>'
.../enclave-0.2.0/lib/enclave.rb:31:in `eval'
.../enclave-0.2.0/lib/enclave.rb:31:in `_eval'

-- Machine register context ------------------------------------------------
  x0: 0x0000000000000020  x1: 0x0000000000000000  x2: 0x0000000000000000
 x19: 0x0000000000000020 x20: 0x0000000000000020 x21: 0x0000000000000001
 x28: 0x0000000000000002

Environment

• enclave 0.2.0
• ruby 3.1.7 [arm64-darwin]