[Bug] Merging objects cause meshes to become ineditable.

Issue: Merging objects cause meshes to become ineditable.

Unity version: 2018.4.21f1
ProBuilder version: 4.2.3

Steps to reproduce:

1. Create a new project and scene with the ProBuilder package installed.
2. Add 2 or more new ProBuilder objects, cubes for example.
3. Select any amount and merge them.
4. Select a face, vertex, edge, or face and attempt to alter the mesh.

You should receive errors such as these:
​

Code (CSharp):

1. KeyNotFoundException: The given key was not present in the dictionary.
2. System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) (at <e1319b7195c343e79b385cd3aa43f5dc>:0)
3. UnityEngine.ProBuilder.ProBuilderMesh.CacheSelection () (at Library/PackageCache/com.unity.probuilder@4.2.3/Runtime/Core/ProBuilderMeshSelection.cs:112)
4. UnityEngine.ProBuilder.ProBuilderMesh.get_selectedSharedVerticesCount () (at Library/PackageCache/com.unity.probuilder@4.2.3/Runtime/Core/ProBuilderMeshSelection.cs:64)
5. UnityEditor.ProBuilder.MeshSelection.RecalculateSelectedComponentCounts () (at Library/PackageCache/com.unity.probuilder@4.2.3/Editor/EditorCore/MeshSelection.cs:268)
6. UnityEditor.ProBuilder.MeshSelection.OnComponentSelectionChanged () (at Library/PackageCache/com.unity.probuilder@4.2.3/Editor/EditorCore/MeshSelection.cs:218)
7. UnityEditor.ProBuilder.MeshSelection.OnObjectSelectionChanged () (at Library/PackageCache/com.unity.probuilder@4.2.3/Editor/EditorCore/MeshSelection.cs:192)
8. UnityEditor.Selection.Internal_CallSelectionChanged () (at C:/buildslave/unity/build/Editor/Mono/Selection.cs:15)

Code (CSharp):

1. GUI Error: You are pushing more GUIClips than you are popping. Make sure they are balanced.
2. UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) (at C:/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:179)
3.  

Some other effects should be that it is difficult to select edges, faces, or vertices.

 

Tools > ProBuilder > Repair > Rebuild Shared Indexes Cache does seem to fix it, but honestly that function should be run when 'Merge objects" is used to avoid confusion.

 

This helped me out a lot, thanks!

 

God bless you, good man!)) thanks!)