Immersive Lanterns Unofficial Fix 1.0.7

Fixed

• Fixed a startup warning where Mixin failed to read an empty reference map for immersivelanterns.mixins.json, caused by a missing refmap key in the mixin config. The mod now emits the same standard, harmless refmap warning as other mods on this toolchain instead of a malformed empty-string message.

No functional changes: this is a cosmetic/logging fix only. (Fixes #1)