Harden export preview handling

frontend/src/components/exports/ExportPreview.tsx

@@ -0,0 +1,16 @@
+interface ExportPreviewProps {
+  content: Record<string, unknown> | null
+}
+
+export function ExportPreview({ content }: ExportPreviewProps): JSX.Element | null {
+  if (!content) {
+    return null
+  }
+
+  return (
+    <section>
+      <h2>Export Preview</h2>
+      <pre className="job-result">{JSON.stringify(content, null, 2)}</pre>
+    </section>
+  )
+}