Swallowed crash when attempting to open mailbox: NoSuchElementException

[LemmaEOF]

[11:15:04] [Server thread/FATAL]: Error executing task on Server
java.util.NoSuchElementException: null
        at java.util.ArrayDeque.removeFirst(ArrayDeque.java:362) ~[?:?]
        at dev.hephaestus.glowcase.block.entity.MailboxBlockEntity.removeMessage(MailboxBlockEntity.java:43) ~[glowcase-1.0.0.jar:?]
        at dev.hephaestus.glowcase.block.MailboxBlock.method_9534(MailboxBlock.java:81) ~[glowcase-1.0.0.jar:?]
        at net.minecraft.class_4970$class_4971.method_26174(class_4970.java:938) ~[intermediary-server.jar:?]
        at net.minecraft.class_3225.method_14262(class_3225.java:327) ~[intermediary-server.jar:?]
        at net.minecraft.class_3244.method_12046(class_3244.java:1050) ~[intermediary-server.jar:?]
        at net.minecraft.class_2885.method_12547(class_2885.java:30) ~[intermediary-server.jar:?]
        at net.minecraft.class_2885.method_11054(class_2885.java:8) ~[intermediary-server.jar:?]
        at net.minecraft.class_2600.method_11072(class_2600.java:21) ~[intermediary-server.jar:?]
        at net.minecraft.class_3738.run(class_3738.java:18) ~[intermediary-server.jar:?]
        at net.minecraft.class_1255.method_18859(class_1255.java:151) ~[intermediary-server.jar:?]
        at net.minecraft.class_4093.method_18859(class_4093.java:23) ~[intermediary-server.jar:?]
        at net.minecraft.server.MinecraftServer.method_24306(MinecraftServer.java:788) ~[intermediary-server.jar:?]
        at net.minecraft.server.MinecraftServer.method_18859(MinecraftServer.java:164) ~[intermediary-server.jar:?]
        at net.minecraft.class_1255.method_16075(class_1255.java:125) ~[intermediary-server.jar:?]
        at net.minecraft.server.MinecraftServer.method_20415(MinecraftServer.java:770) ~[intermediary-server.jar:?]
        at net.minecraft.server.MinecraftServer.method_16075(MinecraftServer.java:764) ~[intermediary-server.jar:?]
        at net.minecraft.class_1255.method_18857(class_1255.java:134) ~[intermediary-server.jar:?]
        at net.minecraft.server.MinecraftServer.method_16208(MinecraftServer.java:749) ~[intermediary-server.jar:?]
        at net.minecraft.server.MinecraftServer.method_29741(MinecraftServer.java:701) ~[intermediary-server.jar:?]
        at net.minecraft.server.MinecraftServer.method_29739(MinecraftServer.java:270) ~[intermediary-server.jar:?]
        at java.lang.Thread.run(Thread.java:831) [?:?]