NPE when repairing nextClaimID

[Borbarad13]

What happened:

During startup the following exception occurs: "[GriefPrevention] Unable to initialize the file system data store."

What you expected:

Normal startup without exception

Steps to reproduce:

This may include a build schematic, a video, or detailed instructions to help reconstruct the issue
I am trying to upgrade from Spigot v12.2 with GriefPrevention v16.7.1 (start up without errors)
to
Spigot v13.1 with GriefPrevention v16.10 (where I receive a null pointer exception)

Stack trace/error or server log

[20:16:48 INFO]: Starting minecraft server version 1.13.1
[20:16:48 INFO]: Loading properties
[20:16:48 INFO]: Default game type: SURVIVAL
[20:16:48 INFO]: This server is running CraftBukkit version git-Spigot-68acb93-7d506c6 (MC: 1.13.1) (Implementing API version 1.13.1-R0.1-SNAPSHOT)
(.........)
[20:16:59 INFO]: [GriefPrevention] Enabling GriefPrevention v16.10
[20:16:59 INFO]: [GriefPrevention] Siege Configuration: Material not found: LONG_GRASS.
[20:16:59 INFO]: [GriefPrevention] Siege Configuration: Material not found: THIN_GLASS.
[20:16:59 INFO]: [GriefPrevention] Siege Configuration: Material not found: WOOD.
[20:16:59 INFO]: [GriefPrevention] Siege Configuration: Material not found: WOOL.
[20:16:59 INFO]: [GriefPrevention] Finished loading configuration.
[20:17:00 INFO]: [GriefPrevention] 52 total claims loaded.
[20:17:00 INFO]: [GriefPrevention] Unable to initialize the file system data store.  Details:
[20:17:00 INFO]: [GriefPrevention] null
[20:17:00 WARN]: java.lang.NullPointerException
[20:17:00 WARN]:        at me.ryanhamshire.GriefPrevention.DataStore.initialize(DataStore.java:144)
[20:17:00 WARN]:        at me.ryanhamshire.GriefPrevention.FlatFileDataStore.initialize(FlatFileDataStore.java:215)
[20:17:00 WARN]:        at me.ryanhamshire.GriefPrevention.FlatFileDataStore.<init>(FlatFileDataStore.java:63)
[20:17:00 WARN]:        at me.ryanhamshire.GriefPrevention.GriefPrevention.onEnable(GriefPrevention.java:303)
[20:17:00 WARN]:        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:264)
[20:17:00 WARN]:        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:339)
[20:17:00 WARN]:        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:403)
[20:17:00 WARN]:        at org.bukkit.craftbukkit.v1_13_R2.CraftServer.enablePlugin(CraftServer.java:428)
[20:17:00 WARN]:        at org.bukkit.craftbukkit.v1_13_R2.CraftServer.enablePlugins(CraftServer.java:342)
[20:17:00 WARN]:        at net.minecraft.server.v1_13_R2.MinecraftServer.l(MinecraftServer.java:584)
[20:17:00 WARN]:        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:546)
[20:17:00 WARN]:        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:424)
[20:17:00 WARN]:        at net.minecraft.server.v1_13_R2.DedicatedServer.init(DedicatedServer.java:294)
[20:17:00 WARN]:        at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:702)
[20:17:00 WARN]:        at java.lang.Thread.run(Unknown Source)
[20:17:00 INFO]: [GriefPrevention] Finished loading data (Database Mode).
[20:17:00 ERROR]: Error occurred while enabling GriefPrevention v16.10 (Is it up to date?)
java.lang.NullPointerException: null
        at me.ryanhamshire.GriefPrevention.FindUnusedClaimsTask.<init>(FindUnusedClaimsTask.java:38) ~[?:?]
        at me.ryanhamshire.GriefPrevention.GriefPrevention.onEnable(GriefPrevention.java:329) ~[?:?]
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:264) ~[spigot.jar:git-Spigot-68acb93-7d506c6]
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:339) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:403) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at org.bukkit.craftbukkit.v1_13_R2.CraftServer.enablePlugin(CraftServer.java:428) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at org.bukkit.craftbukkit.v1_13_R2.CraftServer.enablePlugins(CraftServer.java:342) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at net.minecraft.server.v1_13_R2.MinecraftServer.l(MinecraftServer.java:584) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:546) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:424) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at net.minecraft.server.v1_13_R2.DedicatedServer.init(DedicatedServer.java:294) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:702) [spigot.jar:git-Spigot-68acb93-7d506c6]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_131]

GriefPrevention config.yml

Default values are perfect for most servers. If you want to customize and have a question, look for the answer here first: http://dev.bukkit.org/bukkit-plugins/grief-prevention/pages/setup-and-configuration/

GriefPrevention:
SeaLevelOverrides:
Darkness_7: -1
Darkness_7_nether: -1
Darkness_7_the_end: -1
Adventures: -1
Creative: -1
Farmworld_1: -1
Farmworld_1_nether: -1
Farmworld_1_the_end: -1
Claims:
Mode:
Darkness_7: Survival
Farmworld_1_nether: Disabled
Darkness_7_the_end: Disabled
Farmworld_1: Survival
Creative: SurvivalRequiringClaims
Darkness_7_nether: Survival
Adventures: Survival
Farmworld_1_the_end: Disabled
PreventGlobalMonsterEggs: true
PreventTheft: true
ProtectCreatures: true
PreventButtonsSwitches: true
LockWoodenDoors: true
LockTrapDoors: true
LockFenceGates: true
EnderPearlsRequireAccessTrust: true
ProtectHorses: true
InitialBlocks: 0
Claim Blocks Accrued Per Hour:
Default: 30
Max Accrued Claim Blocks:
Default: 10000
Accrued Idle Threshold: 0
AccruedIdlePercent: 0
AbandonReturnRatio: 1.0
AutomaticNewPlayerClaimsRadius: 4
ExtendIntoGroundDistance: 255
MinimumWidth: 5
MinimumArea: 100
MaximumDepth: 0
InvestigationTool: STICK
ModificationTool: GOLDEN_SHOVEL
Expiration:
ChestClaimDays: 7
UnusedClaimDays: 14
AllClaims:
DaysInactive: 33
ExceptWhenOwnerHasTotalClaimBlocks: 99999
ExceptWhenOwnerHasBonusClaimBlocks: 99999
AutomaticNatureRestoration:
SurvivalWorlds: false
AllowTrappedInAdminClaims: false
MaximumNumberOfClaimsPerPlayer: 10
CreationRequiresWorldGuardBuildPermission: true
PortalGenerationRequiresPermission: false
VillagerTradingRequiresPermission: false
CommandsRequiringAccessTrust: /sethome;/commandblock
DeliverManuals: false
ManualDeliveryDelaySeconds: 600
Spam:
Enabled: true
LoginCooldownSeconds: 60
LoginLogoutNotificationsPerMinute: 5
ChatSlashCommands: /me;/tell;;/w;/msg;/r;/t;/mail;/feedback
WhisperSlashCommands: /tell;/pm;/r;/w;/whisper;/t;/msg;/feedback
WarningMessage: Please reduce your noise level. Spammers will be banned.
BanOffenders: true
BanMessage: Banned for spam.
AllowedIpAddresses: 1.2.3.4; 5.6.7.8
DeathMessageCooldownSeconds: 60
Logout Message Delay In Seconds: 0
PvP:
RulesEnabledInWorld:
Darkness_7: true
Darkness_7_nether: true
Darkness_7_the_end: true
Adventures: true
Creative: true
Farmworld_1: true
Farmworld_1_nether: true
Farmworld_1_the_end: true
ProtectFreshSpawns: false
PunishLogout: false
CombatTimeoutSeconds: 15
AllowCombatItemDrop: true
BlockedSlashCommands: /home;/vanish;/spawn;/tpa
ProtectPlayersInLandClaims:
PlayerOwnedClaims: true
AdministrativeClaims: true
AdministrativeSubdivisions: true
AllowLavaDumpingNearOtherPlayers:
PvPWorlds: true
NonPvPWorlds: false
AllowFlintAndSteelNearOtherPlayers:
PvPWorlds: true
NonPvPWorlds: false
ProtectPetsOutsideLandClaims: false
Economy:
ClaimBlocksPurchaseCost: 0.0
ClaimBlocksSellValue: 0.0
ProtectItemsDroppedOnDeath:
PvPWorlds: false
NonPvPWorlds: true
BlockLandClaimExplosions: true
BlockSurfaceCreeperExplosions: false
BlockSurfaceOtherExplosions: false
LimitSkyTrees: false
LimitTreeGrowth: false
LimitPistonsToLandClaims: false
FireSpreads: false
FireDestroys: true
AdminsGetWhispers: true
AdminsGetSignNotifications: false
SmartBan: true
Mute New Players Using Banned Words: true
MaxPlayersPerIpAddress: 3
Siege:
Worlds:
- Darkness_7
BreakableBlocks:
- DIRT
- GRASS
- LONG_GRASS
- COBBLESTONE
- GRAVEL
- SAND
- GLASS
- WOOD
- WOOL
- SNOW
DoorsOpenDelayInSeconds: 300
EndermenMoveBlocks: true
SilverfishBreakBlocks: true
CreaturesTrampleCrops: true
RabbitsEatCrops: true
HardModeZombiesBreakDoors: false
Database:
URL: ''
UserName: ''
Password: ''
UseBanCommand: false
BanCommandPattern: ban %name% %reason%
Advanced:
fixNegativeClaimblockAmounts: true
Abridged Logs:
Days To Keep: 14
Included Entry Types:
Social Activity: true
Suspicious Activity: true
Administrative Activity: true
Debug: false
Muted Chat Messages: false

### Plugin list (if applicable):
Shopkeepers, xInventories, MultiWorld, VoteRoulette, Some self build ones.