SuperiorSkyblock Error

>.... [14:23:34 WARN]: [SuperiorSkyblock2] Plugin SuperiorSkyblock2 v1 Pre-3 generated an exception while executing task 31017
java.lang.IllegalArgumentException: Async entity add
at com.gmail.filoghost.holographicdisplays.util.Validator.isTrue(Validator.java:27) ~[?:?]
at com.gmail.filoghost.holographicdisplays.nms.v1_15_R1.NmsManagerImpl.addEntityToWorld(NmsManagerImpl.java:104) ~[?:?]
at com.gmail.filoghost.holographicdisplays.nms.v1_15_R1.NmsManagerImpl.spawnNMSItem(NmsManagerImpl.java:75) ~[?:?]
at com.gmail.filoghost.holographicdisplays.object.line.CraftItemLine.spawn(CraftItemLine.java:88) ~[?:?]
at com.gmail.filoghost.holographicdisplays.object.CraftHologram.spawnEntities(CraftHologram.java:299) ~[?:?]
at com.gmail.filoghost.holographicdisplays.object.CraftHologram.refreshAll(CraftHologram.java:246) ~[?:?]
at com.bgsoftware.superiorskyblock.u.j.K(ho:245) ~[?:?]
at com.bgsoftware.superiorskyblock.c.b.K(qk:15) ~[?:?]
at java.lang.Iterable.forEach(Iterable.java:75) ~[?:1.8.0_242]
at com.bgsoftware.superiorskyblock.c.b.K(qk:15) ~[?:?]
at com.bgsoftware.superiorskyblock.r.G.H(uk:102) ~[?:?]
at com.bgsoftware.superiorskyblock.c.C.sortIslands(yf:428) ~[?:?]
at com.bgsoftware.superiorskyblock.r.H.handleBlockPlace(rg:1187) ~[?:?]
at com.bgsoftware.superiorskyblock.r.H.handleBlockPlace(rg:2601) ~[?:?]
at com.bgsoftware.superiorskyblock.listeners.C.K(em:109) ~[?:?]
at org.bukkit.craftbukkit.v1_15_R1.scheduler.CraftTask.run(CraftTask.java:84) ~[patched_1.15.2.jar:git-Paper-136]
at org.bukkit.craftbukkit.v1_15_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:54) ~[patched_1.15.2.jar:git-Paper-136]
at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) ~[patched_1.15.2.jar:git-Paper-136]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_242]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_242]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_242]