The real bug here is Assets\CryptAES\Universal\CryptAES.dll is marked as compatible with .Dot Net backend. But even though we're building for il2cpp, the editor throws an error

ArgumentException: The Assembly PCLCrypto is referenced by CryptAES ('Assets/CryptAES/Universal/CryptAES.dll'). But the dll is not allowed to be included or could not be found.
UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List`1 alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary`2 cache, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:147)
UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String[] paths, System.String[] foldersToSearch, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:185)
UnityEditor.HostView:OnGUI()

Editor shouldn't have tried to extract types from this dll.

To reproduce:
1. Build attached project
2. See the ArgumentException error

Reproducible: 5.5.0a2, 5.4.0b24, 5.3.5p7, 5.2.5f1