The font preview endpoint explicitly rejects .bdf files (glyph rendering
not implemented server-side), returning 400. The JS didn't know this and
called the endpoint for every selected font, causing a noisy 400 on load.
Guard added in updateFontPreview(): if the selected font ends in .bdf,
show "Preview not available for BDF bitmap fonts" and return early instead
of hitting the API.
Co-authored-by: Chuck <chuck@example.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
