fix: warn on malformed items JSON instead of silently swallowing it

[rajarshi1]

Warn on malformed items JSON

Fixes #4

Problem

<folder-gallery> accepts a declarative items attribute as a JSON string. In connectedCallback, parsing it was wrapped in a try/catch with an empty catch block:

try { this._items = JSON.parse(this.getAttribute('items')); } catch (_) { /* ignore malformed */ }

If the JSON is malformed (a typo, a trailing comma, etc.), the element just silently renders an empty gallery with zero indication of why — making it confusing to debug.

Fix

Log a console.warn with the parse error instead of swallowing it:

try { this._items = JSON.parse(this.getAttribute('items')); } catch (err) { console.warn('<folder-gallery> malformed items attribute:', err.message); }

Added a test in tests/element.test.js asserting the warning fires exactly once with a message matching /malformed items attribute/, using vi.spyOn(console, 'warn').

Testing

• npm test — 41/41 passing (up from 40, new test included)
• npm run check — clean
• npm run build — clean (ESM + CJS)

Files changed

• src/folder-gallery-element.js
• tests/element.test.js