upgrade structures and migrate to nextra v4

tsconfig.json

@@ -13,15 +13,22 @@
     "incremental": true,
     "module": "esnext",
     "esModuleInterop": true,
-    "moduleResolution": "node",
+    "moduleResolution": "bundler",
     "resolveJsonModule": true,
     "isolatedModules": true,
-    "jsx": "preserve"
+    "jsx": "preserve",
+    "plugins": [
+      {
+        "name": "next"
+      }
+    ],
+    "strictNullChecks": true
   },
   "include": [
-    "next-env.d.ts",
     "**/*.ts",
-    "**/*.tsx"
+    "**/*.tsx",
+    "next-env.d.ts",
+    ".next/types/**/*.ts"
   ],
   "exclude": [
     "node_modules"