Skill Tree no longer working/causing server problems

After my server auto rebooted this morning Skill Tree plugin is no longer working and causing console errors for players:
NullReferenceException: Object reference not set to an instance of an object Server Exception: Player Update

Redownloaded Skill Tree latest update, reloaded it and this came back in console:
Could not initialize plugin 'SkillTree v1.6.8' (NullReferenceException: Object reference not set to an instance of an object) at Oxide.Plugins.SkillTree.LoadDefaultMessages () [0x000a5] in <4567efe30377461f8ba892a286485be8>:0 at Oxide.Core.Plugins.Plugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x0001d] in <d59b507fd76240e5b62228d0eae39b73>:0 at Oxide.Core.Plugins.CSPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x00000] in <d59b507fd76240e5b62228d0eae39b73>:0 at Oxide.Plugins.CSharpPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x00000] in <42f9bedc659b4f4786eb778d3cd58968>:0 at Oxide.Plugins.RustPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x0028e] in <f503352b0777495abacdc73df41577ac>:0 at Oxide.Core.Plugins.PluginManager.AddPlugin (Oxide.Core.Plugins.Plugin plugin) [0x00027] in <d59b507fd76240e5b62228d0eae39b73>:0 at Oxide.Core.OxideMod.PluginLoaded (Oxide.Core.Plugins.Plugin plugin) [0x00035] in <d59b507fd76240e5b62228d0eae39b73>:0 No previous version to rollback plugin: SkillTree

Please help

Fixed the issue by deleting all the skill tree files and reuploading/reloading plugin.

How was that caused?

I never touched the language file though =/