NullPointerException when right-clicking on a sign

[Bloodlex]

Describe the bug NullPointerException when right-clicking on a sign with a command: https://pastebin.com/Cz7V2Fw1.

The command seems to execute, but generating the mentioned exception.

My config: https://pastebin.com/2DASbe9w blocks.yml: https://pastebin.com/PYiMaVpB

To Reproduce Steps to reproduce the behavior:

1. Create a sign
2. Assign a command to it
3. Right-click a sign

Expected behavior No exception should be thrown.

Environment (please complete the following information):

• OS: Linux
• This server is running Paper version git-Paper-581 (MC: 1.16.5) (Implementing API version 1.16.5-R0.1-SNAPSHOT) Plugins: AcoWorth, ActionHealth, AdvancedLogger, AdvancedRegionMarket, ArmShopBridge, AsyncWorldEdit, AuthMe, BetterBees, BetterHeads, ChestSort, ColoredSigns, CommandBlocks, CommandHelper, CommandNotifier, CommandPanels, ContainerPassthrough, CraftBook, DeathPenalties, Disease, dynmap, Dynmap-WorldGuard, EasyCarts, Essentials, EssentialsChat, GoldenEnchants, GSit, Harbor, HolographicDisplays, Images, InteractiveBooks, JetsAntiAFKPro, Jobs, KeepChunks, LangUtils, Lasso, LastLoginAPI, LeaderHeadsRevamped, LogBlock, LuckPerms, LWC, MobArena, NBTAPI, NexEngine, NoElytra, OpenInv, OreAnnouncer, PetMaster, Pingas, PlaceholderAPI, Plan, PortalFix*, ProtocolLib, PvPManager, QuickShop, QuickShopDynmap, RegionRaid, RegisterCommands, SkinsRestorer, Spartan, SuperVanish, TitleManager, TreeAssist, Vault, WorldEdit, WorldGuard, WorldGuardExtraFlags