The game log outputs the incorrect minimum format version requiring the `pack_format` field in `pack.mcmeta`

Background
Starting from 25w31a, Mojang changed the metadata format of Minecraft packages. To maintain compatibility, the game still supports data packets and resource packages with a minimum format of 15.

Issue
When a pack or resource pack supports multiple versions and the package format is at least 15, if the pack_format field is missing, the game log will incorrectly output the minimum version requiring the pack_format field as 17 instead of 15.
How to reproduce

1. Select "Singleplayer";

2. Create a world;

3. Select "More" and then click "Data Packs";

4. Drag "Raise the Error.zip" into the game;

5. Click "Yes";

6. This packet will display "(Broken or incompatible)", and the game log will incorrectly output the minimum format version requiring pack_format fields.

Expected result
The game log should output a minimum format version requiring pack_format fields to be 15.
Actual result
The game log output require the minimum format for pack_format fields to be 17.