clean code

packages/presentation/src/components/Presentation.tsx

@@ -42,10 +42,7 @@ export const Presentation = (props: PresentationProps): JSX.Element => {
   const { options, isEnabledMarp, children } = props;
   const { revealOptions } = options;
 
-  let marp = false;
-  if (isEnabledMarp) {
-    [marp] = parseSlideFrontmatterInMarkdown(children);
-  }
+  const marp = isEnabledMarp && parseSlideFrontmatterInMarkdown(children)[0];
 
   useEffect(() => {
     let deck: Reveal.Api;

packages/presentation/src/services/growi-marpit.ts

@@ -60,4 +60,4 @@ export const presentationMarpit = new Marp({
   emoji: undefined,
   html: false,
   math: false,
-}).use(lineNumber);
+});