forge 1.20.1 [Bug] ja_jp.json (and other resource pack translations) overridden by embedded en_us.json #1225

Even when a custom resource pack containing assets/dynamictrees/lang/ja_jp.json is loaded, the in-game translations for Dynamic Trees remain in English (or fallback to unlocalized keys if no other language file is available).

Steps to Reproduce:

1. Set the game language to Japanese (ja_jp).
2. Enable a custom resource pack that contains a valid assets/dynamictrees/lang/ja_jp.json.
3. Check the item/block names for Dynamic Trees in-game.

Result:
The custom translation from the resource pack is completely ignored, and the names display in English.

Root Cause:
Upon inspection, the embedded ja_jp.json inside the mod's JAR file contains a JSON syntax error (such as a missing comma or invalid formatting).

When Minecraft attempts to load language files, Language.loadFromJson throws a JsonSyntaxException while parsing the corrupt embedded ja_jp.json. Because ClientLanguage.appendFrom only catches IOException, this uncaught JsonSyntaxException causes appendFrom to abort early. Consequently, any subsequent resource packs in the resource stack for ja_jp.json are skipped and never processed.

If the broken ja_jp.json inside the JAR is removed or fixed, resource packs load as expected.

Suggested Fix:
Please fix the formatting/syntax errors in the mod's embedded ja_jp.json.

Thank you!