im trying to login with authme, but i get a 'No Permission' error (whether oped or deoped) and this appears in console

[George08091]

Description

[Insert description of issue here]

What PEX Saw

Reason: While performing PEX check

Stacktrace:

java.lang.NullPointerException
    at ru.tehkode.permissions.backends.file.FileEntity.getNode(FileEntity.java:48)
    at ru.tehkode.permissions.backends.file.FileEntity.<init>(FileEntity.java:42)
    at ru.tehkode.permissions.backends.file.FileUser.<init>(FileUser.java:39)
    at ru.tehkode.permissions.backends.FileBackend.getUser(FileBackend.java:111)
    at ru.tehkode.permissions.PermissionManager.getUser(PermissionManager.java:116)
    at ru.tehkode.permissions.PermissionManager.getUser(PermissionManager.java:135)
    at ru.tehkode.permissions.bukkit.PermissionsEx.getUser(PermissionsEx.java:201)
    at ru.tehkode.permissions.bukkit.superperms.PermissiblePEX.performCheck(PermissiblePEX.java:150)
    at ru.tehkode.permissions.bukkit.superperms.PermissiblePEX.checkPermission(PermissiblePEX.java:125)
    at ru.tehkode.permissions.bukkit.superperms.PermissiblePEX.hasPermission(PermissiblePEX.java:116)
    at org.bukkit.craftbukkit.v1_5_R3.entity.CraftHumanEntity.hasPermission(CraftHumanEntity.java:111)
    at uk.org.whoami.authme.commands.LoginCommand.onCommand(LoginCommand.java:54)
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
    at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:189)
    at org.bukkit.craftbukkit.v1_5_R3.CraftServer.dispatchCommand(CraftServer.java:523)
    at net.minecraft.server.v1_5_R3.PlayerConnection.handleCommand(PlayerConnection.java:852)
    at net.minecraft.server.v1_5_R3.PlayerConnection.chat(PlayerConnection.java:776)
    at net.minecraft.server.v1_5_R3.PlayerConnection.a(PlayerConnection.java:736)
    at net.minecraft.server.v1_5_R3.Packet3Chat.handle(Packet3Chat.java:44)
    at net.minecraft.server.v1_5_R3.NetworkManager.b(NetworkManager.java:292)
    at net.minecraft.server.v1_5_R3.PlayerConnection.d(PlayerConnection.java:135)
    at net.minecraft.server.v1_5_R3.ServerConnection.b(SourceFile:35)
    at net.minecraft.server.v1_5_R3.DedicatedServerConnection.b(SourceFile:30)
    at net.minecraft.server.v1_5_R3.MinecraftServer.r(MinecraftServer.java:581)
    at net.minecraft.server.v1_5_R3.DedicatedServer.r(DedicatedServer.java:226)
    at net.minecraft.server.v1_5_R3.MinecraftServer.q(MinecraftServer.java:477)
    at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java:410)
    at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:573)

PEX configuration

permissions:
  backend: file
  backends:
    file:
      file: permissions.yml
  superperms: {}

Permissions database

groups:
  default:
    default: true
    permissions:
    - plotme.limit.2
    - essentials.tpa
    - essentials.msg
    - essentials.r
    - plotme.use.add    
    - plotme.use.remove
    - authme.register
    - authme.login```