fix: frontmatter coercion (empty string is falsy)

Jacky Zhao

2023-12-09 2c69b0c97d40f76363d20478cb799ce4b7518e56

 quartz/components/Explorer.tsx

@@ -86,7 +86,7 @@
  function Explorer({ allFiles, displayClass, fileData }: QuartzComponentProps) {
    constructFileTree(allFiles)
    return (
      <div class={`explorer ${displayClass}`}>
      <div class={`explorer ${displayClass ?? ""}`}>
        <button
          type="button"
          id="explorer"