Fix codemirror reference errors

dabit3/next.js-amplify-workshop#21

Author: PenguinBoi12

src/components/pages/editor.tsx

@@ -2,9 +2,14 @@ import { useState, useEffect, useCallback, useMemo } from 'react';
 import { useQuery, useMutation, gql } from '@apollo/client';
 import { Loader } from "@/components/loader";
 
-import SimpleMDE from "react-simplemde-editor";
+import dynamic from "next/dynamic";
 import hljs from 'highlight.js';
 
+const SimpleMDE = dynamic(
+  () => import("react-simplemde-editor"),
+  { ssr: false }
+);
+
 import '@styles/editor.css'
 
 const PAGE_QUERY = gql`