Ensure descriptor in case main request is cached

Editor assessment

The scope is the highlight — fix(plugin-vue) is exactly how monorepo package fixes should be typed — and the subject stays short and period-free. Its weakness is cryptic jargon: 'ensure descriptor' assumes the reader knows this means the SFC descriptor from the Vue compiler, and 'in case main request is cached' describes the guard condition without saying what goes wrong when it is hit — presumably a stale or missing descriptor producing wrong HMR output. An imperative rewrite ('ensure descriptor is resolved when the main request is cached') plus one body sentence on the symptom would transform this from an insider note into a changelog-worthy entry. No issue or PR reference either. The type and patch semantics are correct; clarity for outsiders is what suffers.