sometimes. previous version have this error too.

Failed to call hook 'OnFindBurnable' on plugin 'AutoFuel v1.1.1' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.AutoFuel.OnFindBurnable (BaseOven oven) [0x0006c] in <b63c7fb36ffd41d19368406a61a48150>:0 
  at Oxide.Plugins.AutoFuel.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0019d] in <b63c7fb36ffd41d19368406a61a48150>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <41771c7bc8d246d0b0a34c2f0d27f2cb>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <b0a93b504f034a0db8b1c3d2503c0987>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <b0a93b504f034a0db8b1c3d2503c0987>:0 

Just started on my server today as well.  Unloading/reloading seemed to make it stop after a few seconds.

[2/11/2020 19:54:10] Failed to call hook 'OnFindBurnable' on plugin 'AutoFuel v1.1.1' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.AutoFuel.OnFindBurnable (BaseOven oven) [0x0006c] in <04b0520a1404469589e6dea87506641d>:0 
  at Oxide.Plugins.AutoFuel.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0019d] in <04b0520a1404469589e6dea87506641d>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <33f7c42a56934dae8ec04b11017dce31>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <b0a93b504f034a0db8b1c3d2503c0987>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <b0a93b504f034a0db8b1c3d2503c0987>:0 ​

Failed to call hook 'OnFindBurnable' on plugin 'AutoFuel v1.1.1' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.AutoFuel.OnFindBurnable (BaseOven oven) [0x0006c] in <d4b9238839814c95894367894385ee5b>:0
at Oxide.Plugins.AutoFuel.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0019d] in <d4b9238839814c95894367894385ee5b>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <008b12f41ec4452da1a5497eeb849299>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <ac41dd3599754d448b8c218b34645820>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <ac41dd3599754d448b8c218b34645820>:0

Possible fix with recent update. Let me know if the problem still persists.