P2 fileysstem write fails with utf8Encode error

[vados-cosmonic]

The following component code does not seem to work in a browser context (and may not in a NodeJS context either) when transpiled:

import { getDirectories } from "wasi:filesystem/preopens@0.2.8";

export const test = {
    run() {
        const preopens = getDirectories();
        if (preopens.length === 0) { throw "ERROR: no preopens"; }

        const dirDescriptor = preopens[0][0];
        const newFileRes = dirDescriptor.openAt(
            {symlinkFollow: false},
            "output.txt",
            { create: true },
            { write: true },
        );
        if (newFileRes.tag === "err") {
            throw "ERROR: failed to create new file: " + newFileRes.val;
        }
        const newFileDescriptor = newFileRes.val;

        newFileDescriptor.write(new TextEncoder().encode("hello world!"), 0);

        const syncRes = newFileDescriptor.sync();
        if (syncRes.tag !== "ok") {
            throw "ERROR: failed to sync new file to disk: " + syncRes.val;
        }

        return "SUCCESS: wrote file";
    }
}

The error that is returned is the following (output from a local test):

[browser] log: expected a string
[browser] log: Stack:
[browser] log:   utf8Encode@/tmp/67e786128b1f/sources/initializer.js:66:36
  export_test$run@/tmp/67e786128b1f/sources/initializer.js:6288:28
[browser] log:
[browser] log: Redirecting call to abort() to mozalloc_abort

RuntimeError: unreachable
RuntimeError: unreachable
    at http://127.0.0.1:34397/transpiled/component.core.wasm:wasm-function[12408]:0x88502e
    at http://127.0.0.1:34397/transpiled/component.core.wasm:wasm-function[4500]:0x1aaaac
    at tests:p2-shim/test#run (http://127.0.0.1:34397/transpiled/component.core.wasm:wasm-function[12536]:0x89b54f)
    at run (http://127.0.0.1:34397/transpiled/component.js:13246:15)
    at runTranspiledModuleTest (http://127.0.0.1:34397/index.html:100:27)
    at async http://127.0.0.1:34397/index.html:74:4

Ideally after this is fixed, the preview2-shim browser test should be updated to do more than just open a file and should write contents (and maybe read them back) as well.