Error log on plugin disable

[turtlshell]

11.02 21:52:11 [Server] INFO Disabling GamemodeSwitcher v1.0
11.02 21:52:11 [Server] WARN java.lang.NoSuchFieldException: knownCommands
11.02 21:52:11 [Server] WARN at java.lang.Class.getDeclaredField(Class.java:2070)
11.02 21:52:11 [Server] WARN at primal.util.reflection.Violator.getDeclaredField(Violator.java:123)
11.02 21:52:11 [Server] WARN at primal.util.reflection.V.get(V.java:97)
11.02 21:52:11 [Server] WARN at primal.bukkit.plugin.PrimalPlugin.unregisterCommand(PrimalPlugin.java:102)
11.02 21:52:11 [Server] WARN at primal.bukkit.plugin.PrimalPlugin.unregisterCommands(PrimalPlugin.java:152)
11.02 21:52:11 [Server] WARN at primal.bukkit.plugin.PrimalPlugin.unregisterAll(PrimalPlugin.java:159)
11.02 21:52:11 [Server] WARN at primal.bukkit.plugin.PrimalPlugin.onDisable(PrimalPlugin.java:47)
11.02 21:52:11 [Server] WARN at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:256)
11.02 21:52:11 [Server] WARN at org.bukkit.plugin.java.JavaPluginLoader.disablePlugin(JavaPluginLoader.java:360)
11.02 21:52:11 [Server] WARN at org.bukkit.plugin.SimplePluginManager.disablePlugin(SimplePluginManager.java:437)
11.02 21:52:11 [Server] WARN at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:424)
11.02 21:52:11 [Server] WARN at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:417)
11.02 21:52:11 [Server] WARN at org.bukkit.craftbukkit.v1_13_R2.CraftServer.disablePlugins(CraftServer.java:377)
11.02 21:52:11 [Server] WARN at net.minecraft.server.v1_13_R2.MinecraftServer.stop(MinecraftServer.java:651)
11.02 21:52:11 [Server] WARN at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:873)
11.02 21:52:11 [Server] WARN at java.lang.Thread.run(Thread.java:748)
11.02 21:52:11 [Server] ERROR Error occurred while disabling GamemodeSwitcher v1.0 (Is it up to date?)
11.02 21:52:11 [Server] INFO java.lang.NullPointerException: null
11.02 21:52:11 [Server] INFO at primal.bukkit.plugin.PrimalPlugin.unregisterCommand(PrimalPlugin.java:104) ~[?:?]
11.02 21:52:11 [Server] INFO at primal.bukkit.plugin.PrimalPlugin.unregisterCommands(PrimalPlugin.java:152) ~[?:?]
11.02 21:52:11 [Server] INFO at primal.bukkit.plugin.PrimalPlugin.unregisterAll(PrimalPlugin.java:159) ~[?:?]
11.02 21:52:11 [Server] INFO at primal.bukkit.plugin.PrimalPlugin.onDisable(PrimalPlugin.java:47) ~[?:?]
11.02 21:52:11 [Server] INFO at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:256) ~[patched_1.13.2.jar:git-Paper-522]
11.02 21:52:11 [Server] INFO at org.bukkit.plugin.java.JavaPluginLoader.disablePlugin(JavaPluginLoader.java:360) ~[patched_1.13.2.jar:git-Paper-522]
11.02 21:52:11 [Server] INFO at org.bukkit.plugin.SimplePluginManager.disablePlugin(SimplePluginManager.java:437) ~[patched_1.13.2.jar:git-Paper-522]
11.02 21:52:11 [Server] INFO at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:424) ~[patched_1.13.2.jar:git-Paper-522]
11.02 21:52:11 [Server] INFO at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:417) ~[patched_1.13.2.jar:git-Paper-522]
11.02 21:52:11 [Server] INFO at org.bukkit.craftbukkit.v1_13_R2.CraftServer.disablePlugins(CraftServer.java:377) ~[patched_1.13.2.jar:git-Paper-522]
11.02 21:52:11 [Server] INFO at net.minecraft.server.v1_13_R2.MinecraftServer.stop(MinecraftServer.java:651) ~[patched_1.13.2.jar:git-Paper-522]
11.02 21:52:11 [Server] INFO at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:873) ~[patched_1.13.2.jar:git-Paper-522]
11.02 21:52:11 [Server] INFO at java.lang.Thread.run(Thread.java:748) [?:1.8.0_151]