Add strict to tsconfig.json

Author: wooorm

index.js

@@ -9,7 +9,7 @@ import {convertElement} from 'hast-util-is-element'
  * Check if a node is a heading element (includes `hgroup`!).
  * @type {AssertHeading}
  */
-// @ts-ignore Sure, the assertion matches.
+// @ts-expect-error Sure, the assertion matches.
 export const heading = convertElement([
   'h1',
   'h2',

tsconfig.json

@@ -10,6 +10,7 @@
     "declaration": true,
     "emitDeclarationOnly": true,
     "allowSyntheticDefaultImports": true,
-    "skipLibCheck": true
+    "skipLibCheck": true,
+    "strict": true
   }
 }