Fix Windows Deno directory creation error in runner.js

[Copilot]

📝 Changes Description

On Windows with Deno, pyodide.FS.mkdir() throws errors with empty messages when directories exist, causing the e.message.includes('File exists') check to fail silently.

Fix: Use pyodide.FS.analyzePath() to check directory existence before attempting creation, rather than relying on error message content.

// Before: Error message check fails on Windows (empty message)
try {
    pyodide.FS.mkdir(cur);
} catch (e) {
    if (!(e && e.message && e.message.includes('File exists'))) { ... }
}

// After: Platform-agnostic existence check
const pathInfo = pyodide.FS.analyzePath(cur);
if (!pathInfo.exists) {
    pyodide.FS.mkdir(cur);
}

✅ Contributor Checklist

• Pre-Commit checks are passing (locally and remotely)
• Title of your PR / MR corresponds to the required format
• Commit message follows required format {label}(dspy): {message}

⚠️ Warnings

None.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• dl.deno.land
  • Triggering command: /usr/bin/curl curl -s REDACTED /home/REDACTED/work/dspy/dspy/tests/utils/test_exceptions.py /home/REDACTED/work/dspy/dspy/tests/utils/test_langchain_tool.py /home/REDACTED/work/dspy/dspy/tests/utils/test_unbatchify.py /home/REDACTED/work/dspy/dspy/tests/utils/test_asyncify.py /home/REDACTED/work/dspy/dspy/tests/utils/test_mcp.py /home/REDACTED/work/dspy/dspy/tests/utils/test_settings.py /home/REDACTED/work/dspy/dspy/tests/utils/test_usage_tracker.py /home/REDACTED/work/dspy/dspy/tests/utils/__init__.py /home/REDACTED/work/dspy/dspy/tests/streaming/test_streaming.py (dns block)
  • Triggering command: /usr/bin/curl curl -s REDACTED (dns block)
  • Triggering command: /home/REDACTED/.deno/bin/deno deno run --allow-read=/home/REDACTED/work/dspy/dspy/dspy/primitives/REDACTED.js,/home/REDACTED/.cache/deno /home/REDACTED/work/dspy/dspy/dspy/primitives/REDACTED.js (dns block)
• esm.ubuntu.com
  • Triggering command: /usr/lib/apt/methods/https /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Bug] On windows, code execution using deno does not work because of error description mismatch inside js</issue_title>
<issue_description>### What happened?

Os: windows 11,
dspy Version: 3.0.4
Deno:
deno 2.5.6 (stable, release, x86_64-pc-windows-msvc)
v8 14.0.365.5-rusty
typescript 5.9.2

In the deno script runner.js, when creating a file path with mkdir, existing directory are handled using an error catch like this:
} catch (e) {
if (!(e && e.message && e.message.includes('File exists'))) {
console.log("[DEBUG] Error creating directory in Pyodide file system:", cur, "|", e.message);
}
}
where the script assumes that the error message would contain 'File exists', which is not the case for my version of deno (message is empty for this error).
A more robust approach would be to just test if the directory exists using a function like this:

function directoryExists(path) {
try {
const entry = pyodide.FS.analyzePath(path);
return entry.exists; // True if it's a directory
} catch (e) {
console.log("Error checking directory existence in Pyodide:", e);
return false; // If an error occurs (e.g., path doesn't exist), return false
}
}

I have attached the full updated script that works in my case.

runner.js

Steps to reproduce

When using the code interpreter with file loading:
ex:
dspy.PythonInterpreter({}, enable_read_paths=files_path).execute(expression)

files_path could be any file path and expression can be any expression.
The problem is on
Os: windows 11,
Deno:
deno 2.5.6 (stable, release, x86_64-pc-windows-msvc)
v8 14.0.365.5-rusty
typescript 5.9.2

DSPy version

3.0.4</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Bug] On windows, code execution using deno does not work because of error description mismatch inside js #9107

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