Mystical Realms Modpack Fixes

v1.3.0 - NaN/Infinity health & absorption guard

Feature release. Adds a new always-on vanilla-level protection: a player or mob can no longer get permanently stuck with a corrupted (NaN/Infinity) health or absorption value, and a save that was already corrupted by an earlier bug self-heals the moment it loads — no manual save editing required.

Added

• LivingEntity NaN/Infinity health and absorption guard (always on, client and server): protects the vanilla LivingEntity#setHealth(float) and LivingEntity#setAbsorptionAmount(float) setters from non-finite writes.
• Root cause behind this release: on a live server, a player was hit by a boss mob whose attack computes damage as a percentage of the target's current health (a third-party attribute mechanic). When that percentage attribute was driven to Infinity by a malformed affix roll on the boss, and the target's health landed on exactly 0.0 at the instant of the hit, Infinity × 0.0 = NaN in IEEE-754 float math. That NaN then flowed into the vanilla damage pipeline and was subtracted from health, permanently poisoning it; a similar overheal-to-absorption codepath in the same mechanic poisoned absorption the same way. Direct inspection of the affected player's save file confirmed that only Health and AbsorptionAmount were NaN — every other field, including minecraft:generic.max_health, was completely intact. Because NaN fails every numeric comparison, the vanilla death check (health <= 0) never fired again: the player was stuck alive but unable to be healed, damaged, or killed by normal means.
• Two HEAD-cancellable mixin injections now reject any non-finite write before it can reach the entity's state, keeping the last known-good value and logging a warning naming the entity and the rejected value.
• They also self-heal already-corrupted state: if the value already stored on the entity is itself non-finite (e.g. loaded from a save made before this guard existed), health is reset to getMaxHealth() (or 20.0 as a fallback) and absorption to 0.0, automatically, the moment the entity loads.

Notes

This does not patch whichever third-party mod produced the Infinity/NaN value in the first place — it only hardens vanilla against ever storing a corrupted value it receives, regardless of source.

JAR: utility_nexus_fixes-1.21.1-neoforge-21.1.249-1.3.0.jar

Tag: 1.21.1-neoforge-1.3.0