git: openjdk/jdk-sandbox: json: Add some more detail for invalid type for Json.fromUntyped

[duke]

Changeset: adc5ee4d
Branch: json
Author:    Justin Lu <justin.lu at oracle.com>
Date:      2025-07-01 10:50:57 +0000
URL:       https://git.openjdk.org/jdk-sandbox/commit/adc5ee4d8976ed8f372f65f019a8810a079737c5

Add some more detail for invalid type for Json.fromUntyped

! src/java.base/share/classes/java/util/json/Json.java
! test/jdk/java/util/json/TestJsonObject.java