fix(helper): 🐛 fix throwing error in ChapterHelper using asin before …

…it's assigned

src/helpers/books/audible/ChapterHelper.ts

@@ -131,7 +131,7 @@ class ChapterHelper {
 
 		requiredKeys.forEach((key) => {
 			if (!Object.prototype.hasOwnProperty.call(inputJson, key)) {
-				throw new Error(`Required key: ${key}, does not exist on: ${finalJson.asin}`)
+				throw new Error(`Required key: ${key}, does not exist on: ${this.asin}`)
 			}
 		})