mycmd scheduler errors

org.bukkit.command.CommandException: Unhandled exception during tab completion for command '/mycmd-scheduler add ' in plugin MyCommand v5.7.2
        at org.bukkit.command.PluginCommand.tabComplete(PluginCommand.java:150) ~[paper-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.command.Command.tabComplete(Command.java:93) ~[paper-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.command.SimpleCommandMap.tabComplete(SimpleCommandMap.java:244) ~[paper-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.craftbukkit.v1_18_R2.CraftServer.tabCompleteCommand(CraftServer.java:2231) ~[paper-1.18.2.jar:git-Paper-387]
        at org.bukkit.craftbukkit.v1_18_R2.CraftServer.tabComplete(CraftServer.java:2203) ~[paper-1.18.2.jar:git-Paper-387]
        at org.bukkit.craftbukkit.v1_18_R2.command.BukkitCommandWrapper.getSuggestions(BukkitCommandWrapper.java:58) ~[paper-1.18.2.jar:git-Paper-387]
        at com.mojang.brigadier.tree.ArgumentCommandNode.listSuggestions(ArgumentCommandNode.java:71) ~[brigadier-1.0.18.jar:git-Paper-387]
        at com.mojang.brigadier.CommandDispatcher.getCompletionSuggestions(CommandDispatcher.java:601) ~[paper-1.18.2.jar:?]
        at com.mojang.brigadier.CommandDispatcher.getCompletionSuggestions(CommandDispatcher.java:581) ~[paper-1.18.2.jar:?]
        at net.minecraft.server.network.ServerGamePacketListenerImpl.lambda$handleCustomCommandSuggestions$5(ServerGamePacketListenerImpl.java:838) ~[?:?]
        at net.minecraft.server.TickTask.run(TickTask.java:18) ~[paper-1.18.2.jar:git-Paper-387]
        at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:153) ~[?:?]
        at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:24) ~[?:?]
        at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1400) ~[paper-1.18.2.jar:git-Paper-387]
        at net.minecraft.server.MinecraftServer.d(MinecraftServer.java:188) ~[paper-1.18.2.jar:git-Paper-387]
        at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:126) ~[?:?]
        at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1377) ~[paper-1.18.2.jar:git-Paper-387]
        at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1370) ~[paper-1.18.2.jar:git-Paper-387]
        at net.minecraft.util.thread.BlockableEventLoop.runAllTasks(BlockableEventLoop.java:114) ~[?:?]
        at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1504) ~[paper-1.18.2.jar:git-Paper-387]
        at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1226) ~[paper-1.18.2.jar:git-Paper-387]
        at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:316) ~[paper-1.18.2.jar:git-Paper-387]
        at java.lang.Thread.run(Thread.java:833) ~[?:?]
Caused by: java.lang.NullPointerException: Cannot invoke "org.bukkit.configuration.ConfigurationSection.getKeys(boolean)" because the return value of "org.bukkit.configuration.file.FileConfiguration.getConfigurationSection(String)" is null
        at it.emmerrei.mycommand.commands.completions.GenericCommandsCompletions.onTabComplete(GenericCommandsCompletions.java:608) ~[MyCommand.jar:?]
        at org.bukkit.command.PluginCommand.tabComplete(PluginCommand.java:138) ~[paper-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        ... 22 more