MC-249136 Fix

The mod implements a minimal workaround for MC-249136, a bug where locating buried treasure and shipwreck structures causes a significant server lag spike. Structure location is moved off the server tick loop onto a separate thread, so the work no longer stalls the tick. The author states that nothing else was changed to improve structure location performance, and the fix is limited to keeping gameplay from being significantly impeded.

Map rendering is changed as well. Minecraft's map color palette is costly to compute, so the mod draws the image using a fixed black color value instead of calculating colors, and pixels meant to be black are drawn as fully transparent pixels. A second change makes the handling of state persistence for loaded maps update once inside a player's inventory. The author notes that MC-249136 appears fixed in newer Minecraft versions and that treasure map problems on later releases should be reported on the issue tracker.

The mod runs on the server alone, so players join without installing it. It requires Fabric API and is published for Fabric and Quilt with files for this range. The latest file is 1.0.2 for 1.20.4, released 2023-12-09 on the beta channel. The code is open source under the GNU Lesser General Public License v3.0 only.