Threads demo not working with acorn_interpreter.js

[derwehr]

When replacing

  <script src="../acorn.js"></script>
  <script src="../interpreter.js"></script>

with

  <script src="../acorn_interpreter.js"></script>

in thread.html#L7, like described in the documentation, the demo throws TypeError: Cannot read properties of undefined (reading 'object').

[NeilFraser]

Fixed. Thanks!