d3js visualization fails to render in jupyter notebook

[hackl]

Interactive plot visualizations fail to render in a Jupyter Notebook environment. Interestingly, the plots rendered correctly immediately after installing pathpyG, but after subsequent usage (within the same virtual environment), none of the interactive plots worked anymore.

The issue appears to be related to how pathpyG determines whether to use a CDN-hosted vs. local copy of d3js.

Symptoms

Jupyter shows the following warning:

[W 2026-02-02 20:05:48.718 ServerApp] 404 GET /Users/juergen/cloud/teaching/code/.venv/lib/python3.13/site-packages/pathpyG/visualisations/_d3js/templates/d3.v7.min.js (142c0658ab904379a00fa378ed728aba@::1) 1.29ms referer=http://localhost:8888/notebooks/test.ipynb

As a result, interactive plots do not render.

Observation:

The d3.js backend checks CDN availability and falls back to a local copy:

try:
   urllib.request.urlopen(_CDN_URL, timeout=2)
   self.config["d3js_local"] = self.config.get("d3js_local", False)
except (urllib.error.URLError, urllib.error.HTTPError):
   self.config["d3js_local"] = self.config.get("d3js_local", True)

It appears that the HTTPS request to https://d3js.org/d3.v7.min.js fails in my environment, which triggers fallback to the local file. However, the referenced local file cannot be loaded (404), leading to broken rendering.

Current Workaround

Forcing CDN usage makes the plots render correctly:

self.config["d3js_local"] = False

Additional Issue: Config Override

Even when explicitly setting:

import pathpyG as pp
pp.config["d3js_local"] = False

the value appears to be overwritten later by the exception-handling logic. This is unexpected: user-provided configuration should take precedence over automatic detection.

[M-Lampert]

I've had a look into it and fixed the issues in #309.
It seems that there was some kind of bot protection implemented recently, so that the http request was forbidden. I've also fixed the problem with the config-override, which was caused by assigning self.config values to self.config instead of values from config. Additionally, I fixed the file not found error by embedding the local d3js module file into the HTML so that it can also work without a CDN.