fix: frontmatter coercion (empty string is falsy)

Jacky Zhao

2023-12-09 2c69b0c97d40f76363d20478cb799ce4b7518e56

 quartz/plugins/emitters/index.ts

@@ -7,3 +7,4 @@
export { Static } from "./static"
export { ComponentResources } from "./componentResources"
export { NotFoundPage } from "./404"
export { CNAME } from "./cname"