When healing another person (not yourself) this error comes from the AdminLog lua code

ERROR: General , 1667491042433> 868,395,050> ExceptionLogger.logException> Exception thrown java.lang.RuntimeException: __concat not defined for operands: null and target player: Lily at KahluaUtil.fail line:82.
ERROR: General , 1667491042433> 868,395,050> DebugLogStream.printException> Stack trace:
java.lang.RuntimeException: __concat not defined for operands: null and target player: Lily
at se.krka.kahlua.vm.KahluaUtil.fail(KahluaUtil.java:82)
at se.krka.kahlua.vm.KahluaThread.luaMainloop(KahluaThread.java:805)
at se.krka.kahlua.vm.KahluaThread.call(KahluaThread.java:163)
at se.krka.kahlua.vm.KahluaThread.pcall(KahluaThread.java:1980)
at se.krka.kahlua.vm.KahluaThread.pcallBoolean(KahluaThread.java:1924)
at se.krka.kahlua.integration.LuaCaller.protectedCallBoolean(LuaCaller.java:104)
at zombie.ui.UIElement.onMouseUp(UIElement.java:1228)
at zombie.ui.UIManager.update(UIManager.java:809)
at zombie.GameWindow.logic(GameWindow.java:261)
at zombie.core.profiling.AbstractPerformanceProfileProbe.invokeAndMeasure(AbstractPerformanceProfileProbe.java:71)
at zombie.GameWindow.frameStep(GameWindow.java:764)
at zombie.GameWindow.run_ez(GameWindow.java:680)
at zombie.GameWindow.mainThread(GameWindow.java:494)
at java.base/java.lang.Thread.run(Unknown Source)