Fix internal type error

Author: wooorm

lib/index.js

@@ -137,7 +137,10 @@ function one(state, node) {
       if (state.file && state.location) {
         const doc = String(state.file)
         const loc = location(doc)
-        result.position = {start: loc.toPoint(0), end: loc.toPoint(doc.length)}
+        const start = loc.toPoint(0)
+        const end = loc.toPoint(doc.length)
+        // @ts-expect-error: always defined as we give valid input.
+        result.position = {start, end}
       }
 
       return result