[Unity SDK] Config Dialog not saving data

**Describe the bug**
The config dialog in the Unity Editor is not saving the input data and it is throwing the following errors:
```
NullReferenceException: Object reference not set to an instance of an object
MetaMask.Unity.MetaMaskWindow.LoadSettings (MetaMask.Unity.MetaMaskConfig metaMaskConfig, MetaMask.Transports.Unity.UI.MetaMaskUnityUITransport metaMaskUIConfig, MetaMask.Unity.MetaMaskWindow window) (at Assets/MetaMask/Editor/EditorGUI/MetaMaskWindow.cs:246)
MetaMask.Unity.MetaMaskWindow.ShowWindow () (at Assets/MetaMask/Editor/EditorGUI/MetaMaskWindow.cs:86)
```

```
GUI Error: Invalid GUILayout state in MetaMaskWindow view. Verify that all layout Begin/End calls match
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) (at /Users/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:190)
```

**To Reproduce**
Steps to reproduce the behaviour:
1. In the Unity Editor go to: Window -> MetaMask -> Setup Window
2. Change a few of the values
3. Press Apply
4. See error

**Expected behaviour**
- To be reworked to a better approach

**Screenshots**
-

** Provide environment information**
- MetaMask Unity plugin v1.1.3

**Additional context**
-