Images Never Loading - Staging Branch

Ever since the 1.7 update, custom images for nodes no longer load. I've deleted my custom configuration, allowing the default to load which shows the images you have and the format has not seemed to change. Do you have any ideas as to why?

Attachment is comparison between my config [which is functional on 1.6.11] and the default config.

Just to be clear, this is what the skill tree looks like. 

Thanks. Hopefully that will solve the issue [it was set to skinid].

I assume this was addressed in the rewrite since it didn't affect the icons before even though the same configuration was set to skinid? 

It's been working prior to this update and now it doesn't so something must have changed but regardless, now I'm getting this error:

Failed to call hook 'OnServerInitialized' on plugin 'SkillTree v1.7.0' (ArgumentException: An item with the same key has already been added. Key: Mechanic)
  at System.Collections.Generic.Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) [0x0015a] in <f98723dd4586469db5213ec59da723ca>:0 
  at System.Collections.Generic.Dictionary`2[TKey,TValue].Add (TKey key, TValue value) [0x00000] in <f98723dd4586469db5213ec59da723ca>:0 
  at Oxide.Plugins.SkillTree.OnServerInitialized (System.Boolean initial) [0x018a4] in <87861de8d9654c44aab1b81f176ed015>:0 
  at Oxide.Plugins.SkillTree.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0bfca] in <87861de8d9654c44aab1b81f176ed015>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <112d89ea5d3348c8b949af0ab1a866d2>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <112d89ea5d3348c8b949af0ab1a866d2>:0 

I'm not sure what to do since there's only one node called Mechanic in the config so I'm unsure how a second one would exist. 

Update for potential people in the future: We moved things from the "Vehicles" category into a different category, "Movement" and all of the nodes that we moved there apparently had to be renamed from their original names to something else. "Mechanic" [as shown in the above error] --> "Shadetree Mechanic" or whatever tickles your fancy. It only affected the nodes that we moved so if people have more simplistic changes, it probably won't affect them. 

So now, the images are just white boxes:

where as on our live server, on 1.6.11, they look like this:

I've restarted my client. I've restarted the server. Unsure what else to do, outside of those two things. 

I suppose I should add that line 65 was set to false but I changed it in attempt to fix the issue

Awesome. Thank you so much!