Announce bug

[00:15:54 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'announce' in plugin Announce v1.0.0
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:47) ~[patched_1.15.1.jar:git-Paper-62]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:159) ~[patched_1.15.1.jar:git-Paper-62]
        at org.bukkit.craftbukkit.v1_15_R1.CraftServer.dispatchCommand(CraftServer.java:740) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.PlayerConnection.handleCommand(PlayerConnection.java:1820) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.PlayerConnection.a(PlayerConnection.java:1628) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.PacketPlayInChat.a(PacketPlayInChat.java:47) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.PacketPlayInChat.a(PacketPlayInChat.java:5) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.PlayerConnectionUtils.lambda$ensureMainThread$0(PlayerConnectionUtils.java:23) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.TickTask.run(SourceFile:18) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeTask(IAsyncTaskHandler.java:136) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeNext(IAsyncTaskHandler.java:109) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.MinecraftServer.aZ(MinecraftServer.java:1037) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.MinecraftServer.executeNext(MinecraftServer.java:1030) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:119) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.MinecraftServer.sleepForTick(MinecraftServer.java:1014) ~[patched_1.15.1.jar:git-Paper-62]
        at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:937) ~[patched_1.15.1.jar:git-Paper-62]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_231]
Caused by: java.lang.IllegalArgumentException: Illegal group reference: group index is missing
        at java.util.regex.Matcher.appendReplacement(Unknown Source) ~[?:1.8.0_231]
        at java.util.regex.Matcher.replaceAll(Unknown Source) ~[?:1.8.0_231]
        at java.lang.String.replaceAll(Unknown Source) ~[?:1.8.0_231]
        at dev.reproachful.announce.commands.AnnounceCommand.lambda$onCommand$0(AnnounceCommand.java:27) ~[?:?]
        at java.util.ArrayList.forEach(Unknown Source) ~[?:1.8.0_231]
        at dev.reproachful.announce.commands.AnnounceCommand.onCommand(AnnounceCommand.java:26) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:45) ~[patched_1.15.1.jar:git-Paper-62]
        ... 17 more