Empty chart panel on hub pages with no distribution data

[jonathanpopham]

Bug

Hub/taxonomy pages (e.g. Node Types → Directory, Node Types → Class) show an empty rectangle where the distribution chart should be.

Root Cause

The hub chart data has typeDistribution: null and distributions: {} on single-type taxonomy pages. The JS tries to render a donut chart but finds no data, leaving the .chart-panel container visible but empty.

Example from the page source:

{"entryName":"Class","totalEntities":59,"typeDistribution":null}

Expected Behavior

Either:

1. Populate the distribution data (e.g. breakdown by language, domain, or directory within that node type)
2. Or hide the chart panel when there's no data to display

Where to Look

• internal/pssg/ — hub page data generation (what populates hub-chart-data)
• templates/hub.html — the chart panel markup
• templates/_main.js — hub chart rendering (line ~430)

Affected Pages

Every hub page where there's only one dimension to show — typically Node Types → {specific type}, Languages → {specific language}, etc.