Merge pull request #1584 from akim-bow/custom-error-unknown

fix: update the type of a customError property

Author: SaltyAom

src/error.ts

@@ -320,7 +320,7 @@ export class ValidationError extends Error {
 	/**
 	 * Custom error if provided
 	 */
-	customError?: string
+	customError?: unknown
 
 	constructor(
 		public type: string,